<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
    <!-- Field: Doc-Info; Name: Generator; Value: GoFiler Complete; Version: 5.5b -->
    <!-- Field: Doc-Info; Name: VendorURI; Value: http://www.novaworks.co -->
    <!-- Field: Doc-Info; Name: Status; Value: 0x00000000 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
    <link:roleRef roleURI="http://harrowinc.com/role/Cover" xlink:href="hrow-20200930.xsd#Cover" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/BalanceSheets" xlink:href="hrow-20200930.xsd#BalanceSheets" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/BalanceSheetsParenthetical" xlink:href="hrow-20200930.xsd#BalanceSheetsParenthetical" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/StatementsOfOperations" xlink:href="hrow-20200930.xsd#StatementsOfOperations" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/StatementsOfStockholdersEquity" xlink:href="hrow-20200930.xsd#StatementsOfStockholdersEquity" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/StatementsOfCashFlows" xlink:href="hrow-20200930.xsd#StatementsOfCashFlows" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/DescriptionOfBusinessAndBasisOfPresentation" xlink:href="hrow-20200930.xsd#DescriptionOfBusinessAndBasisOfPresentation" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SummaryOfSignificantAccountingPolicies" xlink:href="hrow-20200930.xsd#SummaryOfSignificantAccountingPolicies" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/Revenues" xlink:href="hrow-20200930.xsd#Revenues" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactions" xlink:href="hrow-20200930.xsd#InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactions" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactions" xlink:href="hrow-20200930.xsd#InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactions" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/Inventories" xlink:href="hrow-20200930.xsd#Inventories" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/PrepaidExpensesAndOtherCurrentAssets" xlink:href="hrow-20200930.xsd#PrepaidExpensesAndOtherCurrentAssets" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/PropertyPlantAndEquipment" xlink:href="hrow-20200930.xsd#PropertyPlantAndEquipment" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/IntangibleAssetsAndGoodwill" xlink:href="hrow-20200930.xsd#IntangibleAssetsAndGoodwill" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/AccountsPayableAndAccruedExpenses" xlink:href="hrow-20200930.xsd#AccountsPayableAndAccruedExpenses" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/Debt" xlink:href="hrow-20200930.xsd#Debt" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/Leases" xlink:href="hrow-20200930.xsd#Leases" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/StockholdersEquityAndStock-basedCompensation" xlink:href="hrow-20200930.xsd#StockholdersEquityAndStock-basedCompensation" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/CommitmentsAndContingencies" xlink:href="hrow-20200930.xsd#CommitmentsAndContingencies" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SegmentInformationAndConcentrations" xlink:href="hrow-20200930.xsd#SegmentInformationAndConcentrations" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SubsequentEvents" xlink:href="hrow-20200930.xsd#SubsequentEvents" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="hrow-20200930.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:href="hrow-20200930.xsd#SummaryOfSignificantAccountingPoliciesTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/RevenuesTables" xlink:href="hrow-20200930.xsd#RevenuesTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactionsTables" xlink:href="hrow-20200930.xsd#InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactionsTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactionsTables" xlink:href="hrow-20200930.xsd#InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactionsTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/InventoriesTables" xlink:href="hrow-20200930.xsd#InventoriesTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/PrepaidExpensesAndOtherCurrentAssetsTables" xlink:href="hrow-20200930.xsd#PrepaidExpensesAndOtherCurrentAssetsTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/PropertyPlantAndEquipmentTables" xlink:href="hrow-20200930.xsd#PropertyPlantAndEquipmentTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/IntangibleAssetsAndGoodwillTables" xlink:href="hrow-20200930.xsd#IntangibleAssetsAndGoodwillTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/AccountsPayableAndAccruedExpensesTables" xlink:href="hrow-20200930.xsd#AccountsPayableAndAccruedExpensesTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/DebtTables" xlink:href="hrow-20200930.xsd#DebtTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/LeasesTables" xlink:href="hrow-20200930.xsd#LeasesTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/StockholdersEquityAndStock-basedCompensationTables" xlink:href="hrow-20200930.xsd#StockholdersEquityAndStock-basedCompensationTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SegmentInformationAndConcentrationsTables" xlink:href="hrow-20200930.xsd#SegmentInformationAndConcentrationsTables" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/DescriptionOfBusinessAndBasisOfPresentationDetailsNarrative" xlink:href="hrow-20200930.xsd#DescriptionOfBusinessAndBasisOfPresentationDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfBasicEarningsPerCommonShareDetails" xlink:href="hrow-20200930.xsd#ScheduleOfBasicEarningsPerCommonShareDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfDilutedCommonEquivalentSharesDetails" xlink:href="hrow-20200930.xsd#ScheduleOfDilutedCommonEquivalentSharesDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfDilutedEarningsPerCommonShareDetails" xlink:href="hrow-20200930.xsd#ScheduleOfDilutedEarningsPerCommonShareDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:href="hrow-20200930.xsd#SummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfDisaggregatedRevenueDetails" xlink:href="hrow-20200930.xsd#ScheduleOfDisaggregatedRevenueDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/RevenuesDetailsNarrative" xlink:href="hrow-20200930.xsd#RevenuesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfCondensedIncomeStatementDetails" xlink:href="hrow-20200930.xsd#ScheduleOfCondensedIncomeStatementDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfCondensedBalanceSheetDetails" xlink:href="hrow-20200930.xsd#ScheduleOfCondensedBalanceSheetDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactionsDetailsNarrative" xlink:href="hrow-20200930.xsd#InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactionsDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SummaryOfCondensedIncomeStatementDetails" xlink:href="hrow-20200930.xsd#SummaryOfCondensedIncomeStatementDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SummaryOfCondensedBalanceSheetDetails" xlink:href="hrow-20200930.xsd#SummaryOfCondensedBalanceSheetDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactionsDetailsNarrative" xlink:href="hrow-20200930.xsd#InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactionsDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfInventoriesDetails" xlink:href="hrow-20200930.xsd#ScheduleOfInventoriesDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfPrepaidExpensesAndOtherCurrentAssetsDetails" xlink:href="hrow-20200930.xsd#ScheduleOfPrepaidExpensesAndOtherCurrentAssetsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfPropertyPlantAndEquipmentDetails" xlink:href="hrow-20200930.xsd#ScheduleOfPropertyPlantAndEquipmentDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/PropertyPlantAndEquipmentDetailsNarrative" xlink:href="hrow-20200930.xsd#PropertyPlantAndEquipmentDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfIntangibleAssetsDetails" xlink:href="hrow-20200930.xsd#ScheduleOfIntangibleAssetsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfAmortizationExpensesForIntangibleAssetsDetails" xlink:href="hrow-20200930.xsd#ScheduleOfAmortizationExpensesForIntangibleAssetsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfEstimatedFutureAmortizationExpenseDetails" xlink:href="hrow-20200930.xsd#ScheduleOfEstimatedFutureAmortizationExpenseDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/IntangibleAssetsAndGoodwillDetailsNarrative" xlink:href="hrow-20200930.xsd#IntangibleAssetsAndGoodwillDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfAccountsPayableAndAccruedExpensesDetails" xlink:href="hrow-20200930.xsd#ScheduleOfAccountsPayableAndAccruedExpensesDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SummaryOfFutureMinimumPaymentsDetails" xlink:href="hrow-20200930.xsd#SummaryOfFutureMinimumPaymentsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/DebtDetailsNarrative" xlink:href="hrow-20200930.xsd#DebtDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfFutureLeasePaymentUnderOperatingLeasesDetails" xlink:href="hrow-20200930.xsd#ScheduleOfFutureLeasePaymentUnderOperatingLeasesDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfFutureLeasePaymentUnderFinanceLeaseDetails" xlink:href="hrow-20200930.xsd#ScheduleOfFutureLeasePaymentUnderFinanceLeaseDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/LeasesDetailsNarrative" xlink:href="hrow-20200930.xsd#LeasesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfStockOptionPlanActivityDetails" xlink:href="hrow-20200930.xsd#ScheduleOfStockOptionPlanActivityDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfFairValueAssumptionsDetails" xlink:href="hrow-20200930.xsd#ScheduleOfFairValueAssumptionsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfStockOptionOutstandingAndExercisableDetails" xlink:href="hrow-20200930.xsd#ScheduleOfStockOptionOutstandingAndExercisableDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfRestrictedStockUnitsActivityDetails" xlink:href="hrow-20200930.xsd#ScheduleOfRestrictedStockUnitsActivityDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfWarrantsActivityDetails" xlink:href="hrow-20200930.xsd#ScheduleOfWarrantsActivityDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfWarrantsOutstandingAndWarrantsExercisableDetails" xlink:href="hrow-20200930.xsd#ScheduleOfWarrantsOutstandingAndWarrantsExercisableDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfStockBasedCompensationGrantedToEmployeesDirectorsConsultantsDetails" xlink:href="hrow-20200930.xsd#ScheduleOfStockBasedCompensationGrantedToEmployeesDirectorsConsultantsDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/StockholdersEquityAndStock-basedCompensationDetailsNarrative" xlink:href="hrow-20200930.xsd#StockholdersEquityAndStock-basedCompensationDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/CommitmentsAndContingenciesDetailsNarrative" xlink:href="hrow-20200930.xsd#CommitmentsAndContingenciesDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/ScheduleOfSegmentNetRevenuesSegmentOperatingExpensesAndSegmentContributionDetails" xlink:href="hrow-20200930.xsd#ScheduleOfSegmentNetRevenuesSegmentOperatingExpensesAndSegmentContributionDetails" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SegmentInformationAndConcentrationsDetailsNarrative" xlink:href="hrow-20200930.xsd#SegmentInformationAndConcentrationsDetailsNarrative" xlink:type="simple" />
    <link:roleRef roleURI="http://harrowinc.com/role/SubsequentEventsDetailsNarrative" xlink:href="hrow-20200930.xsd#SubsequentEventsDetailsNarrative" xlink:type="simple" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll" arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/Cover" xlink:title="00000001 - Document - Cover" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/BalanceSheets" xlink:title="00000002 - Statement - Condensed Consolidated Balance Sheets">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_DiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesLineItems" xlink:label="loc_srtDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_srtDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesLineItems" xlink:to="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SurfaceOphthalmicsMember" xlink:label="loc_HROWSurfaceOphthalmicsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWSurfaceOphthalmicsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MeltPharmaceuticalsMember" xlink:label="loc_HROWMeltPharmaceuticalsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWMeltPharmaceuticalsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaapAssetsAbstract_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesLineItems" xlink:to="loc_us-gaapAssetsAbstract_70" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrentAbstract" xlink:label="loc_us-gaapAssetsCurrentAbstract_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_70" xlink:to="loc_us-gaapAssetsCurrentAbstract_70" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_70" xlink:to="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_70" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherInvestments" xlink:label="loc_us-gaapOtherInvestments_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_70" xlink:to="loc_us-gaapOtherInvestments_70" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaapAccountsReceivableNetCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_70" xlink:to="loc_us-gaapAccountsReceivableNetCurrent_70" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InventoryNet" xlink:label="loc_us-gaapInventoryNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_70" xlink:to="loc_us-gaapInventoryNet_70" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaapPrepaidExpenseAndOtherAssetsCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_70" xlink:to="loc_us-gaapPrepaidExpenseAndOtherAssetsCurrent_70" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaapAssetsCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsCurrentAbstract_70" xlink:to="loc_us-gaapAssetsCurrent_70" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaapPropertyPlantAndEquipmentNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_70" xlink:to="loc_us-gaapPropertyPlantAndEquipmentNet_70" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseRightOfUseAsset" xlink:label="loc_us-gaapOperatingLeaseRightOfUseAsset_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_70" xlink:to="loc_us-gaapOperatingLeaseRightOfUseAsset_70" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaapIntangibleAssetsNetExcludingGoodwill_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_70" xlink:to="loc_us-gaapIntangibleAssetsNetExcludingGoodwill_70" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Investments" xlink:label="loc_us-gaapInvestments_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_70" xlink:to="loc_us-gaapInvestments_70" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_70" xlink:to="loc_us-gaapGoodwill_70" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaapAssets_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetsAbstract_70" xlink:to="loc_us-gaapAssets_70" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtDiscountedFutureNetCashFlowsRelatingToProvedOilAndGasReservesLineItems" xlink:to="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaapLiabilitiesCurrentAbstract_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:to="loc_us-gaapAccountsPayableAndAccruedLiabilitiesCurrent_70" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaapEmployeeRelatedLiabilitiesCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:to="loc_us-gaapEmployeeRelatedLiabilitiesCurrent_70" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ContractWithCustomerLiabilityCurrent" xlink:label="loc_us-gaapContractWithCustomerLiabilityCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:to="loc_us-gaapContractWithCustomerLiabilityCurrent_70" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LoansPayableCurrent" xlink:label="loc_us-gaapLoansPayableCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:to="loc_us-gaapLoansPayableCurrent_70" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NotesPayableCurrent" xlink:label="loc_us-gaapNotesPayableCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:to="loc_us-gaapNotesPayableCurrent_70" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityCurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:to="loc_us-gaapOperatingLeaseLiabilityCurrent_70" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityCurrent" xlink:label="loc_us-gaapFinanceLeaseLiabilityCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:to="loc_us-gaapFinanceLeaseLiabilityCurrent_70" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaapLiabilitiesCurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesCurrentAbstract_70" xlink:to="loc_us-gaapLiabilitiesCurrent_70" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseLiabilityNoncurrent" xlink:label="loc_us-gaapOperatingLeaseLiabilityNoncurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapOperatingLeaseLiabilityNoncurrent_70" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseLiabilityNoncurrent" xlink:label="loc_us-gaapFinanceLeaseLiabilityNoncurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapFinanceLeaseLiabilityNoncurrent_70" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesNoncurrent" xlink:label="loc_us-gaapAccountsPayableAndAccruedLiabilitiesNoncurrent_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapAccountsPayableAndAccruedLiabilitiesNoncurrent_70" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermLoansPayable" xlink:label="loc_us-gaapLongTermLoansPayable_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapLongTermLoansPayable_70" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongTermNotesPayable" xlink:label="loc_us-gaapLongTermNotesPayable_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapLongTermNotesPayable_70" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaapLiabilities_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapLiabilities_70" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommitmentsAndContingencies" xlink:label="loc_us-gaapCommitmentsAndContingencies_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapCommitmentsAndContingencies_70" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityAbstract" xlink:label="loc_us-gaapStockholdersEquityAbstract_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapStockholdersEquityAbstract_70" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockValue" xlink:label="loc_us-gaapCommonStockValue_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_70" xlink:to="loc_us-gaapCommonStockValue_70" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaapAdditionalPaidInCapital_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_70" xlink:to="loc_us-gaapAdditionalPaidInCapital_70" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsAccumulatedDeficit" xlink:label="loc_us-gaapRetainedEarningsAccumulatedDeficit_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_70" xlink:to="loc_us-gaapRetainedEarningsAccumulatedDeficit_70" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_70" xlink:to="loc_us-gaapStockholdersEquity_70" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterest" xlink:label="loc_us-gaapMinorityInterest_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_70" xlink:to="loc_us-gaapMinorityInterest_70" xlink:type="arc" order="36" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaapStockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStockholdersEquityAbstract_70" xlink:to="loc_us-gaapStockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_70" xlink:type="arc" order="37" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquity_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLiabilitiesAndStockholdersEquityAbstract_70" xlink:to="loc_us-gaapLiabilitiesAndStockholdersEquity_70" xlink:type="arc" order="38" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/BalanceSheetsParenthetical" xlink:title="00000003 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/StatementsOfOperations" xlink:title="00000004 - Statement - Condensed Consolidated Statements of Operations (Unaudited)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srtProductOrServiceAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_srtProductOrServiceAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srtProductsAndServicesDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtProductOrServiceAxis" xlink:to="loc_srtProductsAndServicesDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srtProductsAndServicesDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtProductOrServiceAxis" xlink:to="loc_srtProductsAndServicesDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ProductSalesNetMember" xlink:label="loc_HROWProductSalesNetMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtProductsAndServicesDomain" xlink:to="loc_HROWProductSalesNetMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_OtherRevenuesMember" xlink:label="loc_HROWOtherRevenuesMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtProductsAndServicesDomain" xlink:to="loc_HROWOtherRevenuesMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MeltPharmaceuticalsMember" xlink:label="loc_HROWMeltPharmaceuticalsMember_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWMeltPharmaceuticalsMember_120" xlink:type="arc" order="121" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SurfaceOphthalmicsMember" xlink:label="loc_HROWSurfaceOphthalmicsMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWSurfaceOphthalmicsMember_160" xlink:type="arc" order="161" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_EtonPharmaceuticalsMember" xlink:label="loc_HROWEtonPharmaceuticalsMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWEtonPharmaceuticalsMember_200" xlink:type="arc" order="201" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaapRevenuesAbstract_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapRevenuesAbstract_250" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRevenuesAbstract_250" xlink:to="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_250" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="loc_us-gaapCostOfGoodsAndServicesSold_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapCostOfGoodsAndServicesSold_250" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaapGrossProfit_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapGrossProfit_250" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="loc_us-gaapOperatingExpensesAbstract_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOperatingExpensesAbstract_250" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="loc_us-gaapSellingGeneralAndAdministrativeExpense_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapOperatingExpensesAbstract_250" xlink:to="loc_us-gaapSellingGeneralAndAdministrativeExpense_250" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaapResearchAndDevelopmentExpense_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapOperatingExpensesAbstract_250" xlink:to="loc_us-gaapResearchAndDevelopmentExpense_250" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="loc_us-gaapImpairmentOfLongLivedAssetsHeldForUse_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapOperatingExpensesAbstract_250" xlink:to="loc_us-gaapImpairmentOfLongLivedAssetsHeldForUse_250" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaapOperatingExpenses_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapOperatingExpensesAbstract_250" xlink:to="loc_us-gaapOperatingExpenses_250" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapOperatingIncomeLoss_250" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonoperatingIncomeExpenseAbstract" xlink:label="loc_us-gaapNonoperatingIncomeExpenseAbstract_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNonoperatingIncomeExpenseAbstract_250" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InterestIncomeExpenseNet" xlink:label="loc_us-gaapInterestIncomeExpenseNet_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapNonoperatingIncomeExpenseAbstract_250" xlink:to="loc_us-gaapInterestIncomeExpenseNet_250" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnInvestments" xlink:label="loc_us-gaapGainLossOnInvestments_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapNonoperatingIncomeExpenseAbstract_250" xlink:to="loc_us-gaapGainLossOnInvestments_250" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaapOtherNonoperatingIncomeExpense_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapNonoperatingIncomeExpenseAbstract_250" xlink:to="loc_us-gaapOtherNonoperatingIncomeExpense_250" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NonoperatingIncomeExpense" xlink:label="loc_us-gaapNonoperatingIncomeExpense_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapNonoperatingIncomeExpenseAbstract_250" xlink:to="loc_us-gaapNonoperatingIncomeExpense_250" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest" xlink:label="loc_us-gaapIncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_250" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeTaxExpenseBenefit" xlink:label="loc_us-gaapIncomeTaxExpenseBenefit_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapIncomeTaxExpenseBenefit_250" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaapProfitLoss_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapProfitLoss_250" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest" xlink:label="loc_us-gaapNetIncomeLossAttributableToNoncontrollingInterest_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNetIncomeLossAttributableToNoncontrollingInterest_250" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNetIncomeLoss_250" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaapEarningsPerShareBasic_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEarningsPerShareBasic_250" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaapEarningsPerShareDiluted_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapEarningsPerShareDiluted_250" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaapWeightedAverageNumberOfSharesOutstandingBasic_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapWeightedAverageNumberOfSharesOutstandingBasic_250" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaapWeightedAverageNumberOfDilutedSharesOutstanding_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapWeightedAverageNumberOfDilutedSharesOutstanding_250" xlink:type="arc" order="23" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/StatementsOfStockholdersEquity" xlink:title="00000005 - Statement - Condensed Consolidated Statements of Stockholders&apos; Equity (Unaudited)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaapAdditionalPaidInCapitalMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapAdditionalPaidInCapitalMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaapRetainedEarningsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapRetainedEarningsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ParentMember" xlink:label="loc_us-gaapParentMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapParentMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="loc_us-gaapNoncontrollingInterestMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapNoncontrollingInterestMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaapStockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_70" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaapSharesOutstanding_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharesOutstanding_70" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_StockIssuedDuringPeriodForExerciseOfWarrants" xlink:label="loc_HROWStockIssuedDuringPeriodForExerciseOfWarrants_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_HROWStockIssuedDuringPeriodForExerciseOfWarrants_70" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_StockIssuedDuringPeriodSharesForExerciseOfWarrants" xlink:label="loc_HROWStockIssuedDuringPeriodSharesForExerciseOfWarrants_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_HROWStockIssuedDuringPeriodSharesForExerciseOfWarrants_70" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeBenefitPlan" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueEmployeeBenefitPlan_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueEmployeeBenefitPlan_70" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeBenefitPlan" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesEmployeeBenefitPlan_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesEmployeeBenefitPlan_70" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueShareBasedCompensation_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueShareBasedCompensation_70" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesShareBasedCompensation_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesShareBasedCompensation_70" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue" xlink:label="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_70" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueRestrictedStockAwardGross_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueRestrictedStockAwardGross_70" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesRestrictedStockAwardGross_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesRestrictedStockAwardGross_70" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProfitLoss" xlink:label="loc_us-gaapProfitLoss_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapProfitLoss_70" xlink:type="arc" order="12" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/StatementsOfCashFlows" xlink:title="00000006 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/DescriptionOfBusinessAndBasisOfPresentation" xlink:title="00000007 - Disclosure - DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SummaryOfSignificantAccountingPolicies" xlink:title="00000008 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/Revenues" xlink:title="00000009 - Disclosure - REVENUES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactions" xlink:title="00000010 - Disclosure - INVESTMENT IN MELT PHARMACEUTICALS, INC. AND AGREEMENTS - RELATED PARTY TRANSACTIONS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactions" xlink:title="00000011 - Disclosure - INVESTMENT IN SURFACE OPHTHALMICS, INC. AND AGREEMENTS - RELATED PARTY TRANSACTIONS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/Inventories" xlink:title="00000012 - Disclosure - INVENTORIES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/PrepaidExpensesAndOtherCurrentAssets" xlink:title="00000013 - Disclosure - PREPAID EXPENSES AND OTHER CURRENT ASSETS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/PropertyPlantAndEquipment" xlink:title="00000014 - Disclosure - PROPERTY, PLANT AND EQUIPMENT" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/IntangibleAssetsAndGoodwill" xlink:title="00000015 - Disclosure - INTANGIBLE ASSETS AND GOODWILL" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/AccountsPayableAndAccruedExpenses" xlink:title="00000016 - Disclosure - ACCOUNTS PAYABLE AND ACCRUED EXPENSES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/Debt" xlink:title="00000017 - Disclosure - DEBT" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/Leases" xlink:title="00000018 - Disclosure - LEASES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/StockholdersEquityAndStock-basedCompensation" xlink:title="00000019 - Disclosure - STOCKHOLDERS&#8217; EQUITY AND STOCK-BASED COMPENSATION" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/CommitmentsAndContingencies" xlink:title="00000020 - Disclosure - COMMITMENTS AND CONTINGENCIES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SegmentInformationAndConcentrations" xlink:title="00000021 - Disclosure - SEGMENT INFORMATION AND CONCENTRATIONS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SubsequentEvents" xlink:title="00000022 - Disclosure - SUBSEQUENT EVENTS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:title="00000023 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SummaryOfSignificantAccountingPoliciesTables" xlink:title="00000024 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/RevenuesTables" xlink:title="00000025 - Disclosure - REVENUES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactionsTables" xlink:title="00000026 - Disclosure - INVESTMENT IN MELT PHARMACEUTICALS, INC. AND AGREEMENTS - RELATED PARTY TRANSACTIONS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactionsTables" xlink:title="00000027 - Disclosure - INVESTMENT IN SURFACE OPHTHALMICS, INC. AND AGREEMENTS - RELATED PARTY TRANSACTIONS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/InventoriesTables" xlink:title="00000028 - Disclosure - INVENTORIES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/PrepaidExpensesAndOtherCurrentAssetsTables" xlink:title="00000029 - Disclosure - PREPAID EXPENSES AND OTHER CURRENT ASSETS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/PropertyPlantAndEquipmentTables" xlink:title="00000030 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/IntangibleAssetsAndGoodwillTables" xlink:title="00000031 - Disclosure - INTANGIBLE ASSETS AND GOODWILL (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/AccountsPayableAndAccruedExpensesTables" xlink:title="00000032 - Disclosure - ACCOUNTS PAYABLE AND ACCRUED EXPENSES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/DebtTables" xlink:title="00000033 - Disclosure - DEBT (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/LeasesTables" xlink:title="00000034 - Disclosure - LEASES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/StockholdersEquityAndStock-basedCompensationTables" xlink:title="00000035 - Disclosure - STOCKHOLDERS&#8217; EQUITY AND STOCK-BASED COMPENSATION (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SegmentInformationAndConcentrationsTables" xlink:title="00000036 - Disclosure - SEGMENT INFORMATION AND CONCENTRATIONS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/DescriptionOfBusinessAndBasisOfPresentationDetailsNarrative" xlink:title="00000037 - Disclosure - DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaapBusinessAcquisitionLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipAxis" xlink:label="loc_srtOwnershipAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_srtOwnershipAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipDomain" xlink:label="loc_srtOwnershipDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtOwnershipAxis" xlink:to="loc_srtOwnershipDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_OwnershipDomain" xlink:label="loc_srtOwnershipDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtOwnershipAxis" xlink:to="loc_srtOwnershipDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MayfieldPharmaceuticalsIncMember" xlink:label="loc_HROWMayfieldPharmaceuticalsIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtOwnershipDomain" xlink:to="loc_HROWMayfieldPharmaceuticalsIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_StowePharmaceuticalsIncMember" xlink:label="loc_HROWStowePharmaceuticalsIncMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtOwnershipDomain" xlink:to="loc_HROWStowePharmaceuticalsIncMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_TGVHealthLLCMember" xlink:label="loc_HROWTGVHealthLLCMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWTGVHealthLLCMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="loc_us-gaapEquityMethodInvestmentOwnershipPercentage_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_us-gaapEquityMethodInvestmentOwnershipPercentage_90" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ConsolidationBasisDescription" xlink:label="loc_HROWConsolidationBasisDescription_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_HROWConsolidationBasisDescription_90" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_us-gaapOperatingIncomeLoss_90" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RetainedEarningsAccumulatedDeficit1" xlink:label="loc_HROWRetainedEarningsAccumulatedDeficit1_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_HROWRetainedEarningsAccumulatedDeficit1_90" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaapNetCashProvidedByUsedInOperatingActivities_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_us-gaapNetCashProvidedByUsedInOperatingActivities_90" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionLineItems" xlink:to="loc_us-gaapCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_90" xlink:type="arc" order="5" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfBasicEarningsPerCommonShareDetails" xlink:title="00000038 - Disclosure - SCHEDULE OF BASIC EARNINGS PER COMMON SHARE (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfDilutedCommonEquivalentSharesDetails" xlink:title="00000039 - Disclosure - SCHEDULE OF DILUTED COMMON EQUIVALENT SHARES (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:label="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:label="loc_us-gaapScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:to="loc_us-gaapScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:label="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable" xlink:to="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaapAntidilutiveSecuritiesNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AntidilutiveSecuritiesNameDomain" xlink:label="loc_us-gaapAntidilutiveSecuritiesNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis" xlink:to="loc_us-gaapAntidilutiveSecuritiesNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaapWarrantMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_us-gaapWarrantMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_StockOptionsMember" xlink:label="loc_HROWStockOptionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesNameDomain" xlink:to="loc_HROWStockOptionsMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WeightedAverageNumberDilutedSharesOutstandingAdjustment" xlink:label="loc_us-gaapWeightedAverageNumberDilutedSharesOutstandingAdjustment_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" xlink:to="loc_us-gaapWeightedAverageNumberDilutedSharesOutstandingAdjustment_40" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfDilutedEarningsPerCommonShareDetails" xlink:title="00000040 - Disclosure - SCHEDULE OF DILUTED EARNINGS PER COMMON SHARE (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:title="00000041 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityListingsLineItems" xlink:label="loc_deiEntityListingsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_EtonPharmaceuticalsIncMember" xlink:label="loc_HROWEtonPharmaceuticalsIncMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWEtonPharmaceuticalsIncMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MeltPharmaceuticalsIncMember" xlink:label="loc_HROWMeltPharmaceuticalsIncMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWMeltPharmaceuticalsIncMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SurfacePharmaceuticalsIncMember" xlink:label="loc_HROWSurfacePharmaceuticalsIncMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWSurfacePharmaceuticalsIncMember_130" xlink:type="arc" order="131" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SeriesAPreferredStockMember" xlink:label="loc_us-gaapSeriesAPreferredStockMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesAPreferredStockMember_50" xlink:type="arc" order="52" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_MinorityInterestDescription" xlink:label="loc_us-gaapMinorityInterestDescription_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapMinorityInterestDescription_190" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_UnvestedRestrictedStockUnits" xlink:label="loc_HROWUnvestedRestrictedStockUnits_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_HROWUnvestedRestrictedStockUnits_190" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_VestedRestrictedStockUnits" xlink:label="loc_HROWVestedRestrictedStockUnits_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_HROWVestedRestrictedStockUnits_190" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NumberOfSharesOwned" xlink:label="loc_HROWNumberOfSharesOwned_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_HROWNumberOfSharesOwned_190" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="loc_us-gaapEquityMethodInvestmentOwnershipPercentage_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapEquityMethodInvestmentOwnershipPercentage_190" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharesIssuedPricePerShare" xlink:label="loc_us-gaapSharesIssuedPricePerShare_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapSharesIssuedPricePerShare_190" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GainLossOnInvestments" xlink:label="loc_us-gaapGainLossOnInvestments_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapGainLossOnInvestments_190" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_InvestmentOwnedAtFairValue" xlink:label="loc_us-gaapInvestmentOwnedAtFairValue_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapInvestmentOwnedAtFairValue_190" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ProceedsFromIssuanceOfPreferredStockAndPreferenceStock" xlink:label="loc_us-gaapProceedsFromIssuanceOfPreferredStockAndPreferenceStock_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfPreferredStockAndPreferenceStock_190" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeconsolidationGainOrLossAmount" xlink:label="loc_us-gaapDeconsolidationGainOrLossAmount_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapDeconsolidationGainOrLossAmount_190" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_UnrealizedGainLossOnInvestments" xlink:label="loc_us-gaapUnrealizedGainLossOnInvestments_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapUnrealizedGainLossOnInvestments_190" xlink:type="arc" order="10" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfDisaggregatedRevenueDetails" xlink:title="00000042 - Disclosure - SCHEDULE OF DISAGGREGATED REVENUE (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueLineItems" xlink:label="loc_us-gaapDisaggregationOfRevenueLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaapDisaggregationOfRevenueTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDisaggregationOfRevenueLineItems" xlink:to="loc_us-gaapDisaggregationOfRevenueTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srtProductOrServiceAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDisaggregationOfRevenueTable" xlink:to="loc_srtProductOrServiceAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srtProductsAndServicesDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtProductOrServiceAxis" xlink:to="loc_srtProductsAndServicesDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srtProductsAndServicesDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtProductOrServiceAxis" xlink:to="loc_srtProductsAndServicesDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ProductSalesNetMember" xlink:label="loc_HROWProductSalesNetMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtProductsAndServicesDomain" xlink:to="loc_HROWProductSalesNetMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_CommissionsMember" xlink:label="loc_HROWCommissionsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtProductsAndServicesDomain" xlink:to="loc_HROWCommissionsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LicenseMember" xlink:label="loc_us-gaapLicenseMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtProductsAndServicesDomain" xlink:to="loc_us-gaapLicenseMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDisaggregationOfRevenueLineItems" xlink:to="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_170" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/RevenuesDetailsNarrative" xlink:title="00000043 - Disclosure - REVENUES (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfCondensedIncomeStatementDetails" xlink:title="00000044 - Disclosure - SCHEDULE OF CONDENSED INCOME STATEMENT (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityListingsLineItems" xlink:label="loc_deiEntityListingsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MeltPharmaceuticalsIncMember" xlink:label="loc_HROWMeltPharmaceuticalsIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWMeltPharmaceuticalsIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_20" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapOperatingIncomeLoss_20" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapNetIncomeLoss_20" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfCondensedBalanceSheetDetails" xlink:title="00000045 - Disclosure - SCHEDULE OF CONDENSED BALANCE SHEET (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityListingsLineItems" xlink:label="loc_deiEntityListingsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MeltPharmaceuticalsIncMember" xlink:label="loc_HROWMeltPharmaceuticalsIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWMeltPharmaceuticalsIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaapAssetsCurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapAssetsCurrent_20" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsNoncurrent" xlink:label="loc_us-gaapAssetsNoncurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapAssetsNoncurrent_20" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaapAssets_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapAssets_20" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaapLiabilities_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapLiabilities_20" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStockholdersEquity_20" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquity_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapLiabilitiesAndStockholdersEquity_20" xlink:type="arc" order="5" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/InvestmentInMeltPharmaceuticalsInc.AndAgreements-RelatedPartyTransactionsDetailsNarrative" xlink:title="00000046 - Disclosure - INVESTMENT IN MELT PHARMACEUTICALS, INC. AND AGREEMENTS - RELATED PARTY TRANSACTIONS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityListingsLineItems" xlink:label="loc_deiEntityListingsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MeltPharmaceuticalsIncMember" xlink:label="loc_HROWMeltPharmaceuticalsIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWMeltPharmaceuticalsIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_AssetPurchaseAgreementMember" xlink:label="loc_HROWAssetPurchaseAgreementMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWAssetPurchaseAgreementMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ManagementServicesAgreementMember" xlink:label="loc_HROWManagementServicesAgreementMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWManagementServicesAgreementMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RoyaltyPaymentPercentageOnNetSales" xlink:label="loc_HROWRoyaltyPaymentPercentageOnNetSales_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_HROWRoyaltyPaymentPercentageOnNetSales_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdministrativeFeesExpense" xlink:label="loc_us-gaapAdministrativeFeesExpense_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapAdministrativeFeesExpense_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DueFromRelatedParties" xlink:label="loc_us-gaapDueFromRelatedParties_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapDueFromRelatedParties_40" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SummaryOfCondensedIncomeStatementDetails" xlink:title="00000047 - Disclosure -  SUMMARY OF CONDENSED INCOME STATEMENT (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityListingsLineItems" xlink:label="loc_deiEntityListingsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SurfacePharmaceuticalsIncMember" xlink:label="loc_HROWSurfacePharmaceuticalsIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWSurfacePharmaceuticalsIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_20" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapOperatingIncomeLoss_20" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapNetIncomeLoss_20" xlink:type="arc" order="2" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SummaryOfCondensedBalanceSheetDetails" xlink:title="00000048 - Disclosure - SUMMARY OF CONDENSED BALANCE SHEET (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityListingsLineItems" xlink:label="loc_deiEntityListingsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SurfacePharmaceuticalsIncMember" xlink:label="loc_HROWSurfacePharmaceuticalsIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWSurfacePharmaceuticalsIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaapAssetsCurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapAssetsCurrent_20" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetsNoncurrent" xlink:label="loc_us-gaapAssetsNoncurrent_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapAssetsNoncurrent_20" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaapAssets_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapAssets_20" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaapLiabilities_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapLiabilities_20" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaapStockholdersEquity_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStockholdersEquity_20" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaapLiabilitiesAndStockholdersEquity_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapLiabilitiesAndStockholdersEquity_20" xlink:type="arc" order="5" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/InvestmentInSurfaceOphthalmicsInc.AndAgreements-RelatedPartyTransactionsDetailsNarrative" xlink:title="00000049 - Disclosure - INVESTMENT IN SURFACE OPHTHALMICS, INC. AND AGREEMENTS - RELATED PARTY TRANSACTIONS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityListingsLineItems" xlink:label="loc_deiEntityListingsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SurfacePharmaceuticalsIncMember" xlink:label="loc_HROWSurfacePharmaceuticalsIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWSurfacePharmaceuticalsIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_AssetPurchaseAndLicenseAgreementMember" xlink:label="loc_HROWAssetPurchaseAndLicenseAgreementMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWAssetPurchaseAndLicenseAgreementMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_0" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_10" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_DrLindstromMember" xlink:label="loc_HROWDrLindstromMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWDrLindstromMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RoyaltyPaymentPercentageOnNetSales" xlink:label="loc_HROWRoyaltyPaymentPercentageOnNetSales_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_HROWRoyaltyPaymentPercentageOnNetSales_40" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfInventoriesDetails" xlink:title="00000050 - Disclosure - SCHEDULE OF INVENTORIES (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfPrepaidExpensesAndOtherCurrentAssetsDetails" xlink:title="00000051 - Disclosure - SCHEDULE OF PREPAID EXPENSES AND OTHER CURRENT ASSETS (Details)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityListingsLineItems" xlink:label="loc_deiEntityListingsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MeltPharmaceuticalsIncMember" xlink:label="loc_HROWMeltPharmaceuticalsIncMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWMeltPharmaceuticalsIncMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PrepaidInsurance" xlink:label="loc_us-gaapPrepaidInsurance_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapPrepaidInsurance_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherPrepaidExpenseCurrent" xlink:label="loc_us-gaapOtherPrepaidExpenseCurrent_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapOtherPrepaidExpenseCurrent_50" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DueFromRelatedPartiesCurrent" xlink:label="loc_us-gaapDueFromRelatedPartiesCurrent_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapDueFromRelatedPartiesCurrent_50" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaapOtherAssetsCurrent_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_us-gaapOtherAssetsCurrent_50" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_PrepaidExpenseAndOtherAssetsCurrent1" xlink:label="loc_HROWPrepaidExpenseAndOtherAssetsCurrent1_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityListingsLineItems" xlink:to="loc_HROWPrepaidExpenseAndOtherAssetsCurrent1_50" xlink:type="arc" order="4" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfPropertyPlantAndEquipmentDetails" xlink:title="00000052 - Disclosure - SCHEDULE OF PROPERTY, PLANT AND EQUIPMENT (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/PropertyPlantAndEquipmentDetailsNarrative" xlink:title="00000053 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongLivedAssetsHeldForSaleLineItems" xlink:label="loc_us-gaapLongLivedAssetsHeldForSaleLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfLongLivedAssetsHeldForSaleTable" xlink:label="loc_us-gaapScheduleOfLongLivedAssetsHeldForSaleTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLongLivedAssetsHeldForSaleLineItems" xlink:to="loc_us-gaapScheduleOfLongLivedAssetsHeldForSaleTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongLivedAssetsHeldForSaleByAssetTypeAxis" xlink:label="loc_us-gaapLongLivedAssetsHeldForSaleByAssetTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfLongLivedAssetsHeldForSaleTable" xlink:to="loc_us-gaapLongLivedAssetsHeldForSaleByAssetTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongLivedAssetsHeldForSaleNameDomain" xlink:label="loc_us-gaapLongLivedAssetsHeldForSaleNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapLongLivedAssetsHeldForSaleByAssetTypeAxis" xlink:to="loc_us-gaapLongLivedAssetsHeldForSaleNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LongLivedAssetsHeldForSaleNameDomain" xlink:label="loc_us-gaapLongLivedAssetsHeldForSaleNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLongLivedAssetsHeldForSaleByAssetTypeAxis" xlink:to="loc_us-gaapLongLivedAssetsHeldForSaleNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ParkRestructuringMember" xlink:label="loc_HROWParkRestructuringMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLongLivedAssetsHeldForSaleNameDomain" xlink:to="loc_HROWParkRestructuringMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DepreciationAmortizationAndAccretionNet" xlink:label="loc_us-gaapDepreciationAmortizationAndAccretionNet_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLongLivedAssetsHeldForSaleLineItems" xlink:to="loc_us-gaapDepreciationAmortizationAndAccretionNet_70" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaapAssetImpairmentCharges_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLongLivedAssetsHeldForSaleLineItems" xlink:to="loc_us-gaapAssetImpairmentCharges_70" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfIntangibleAssetsDetails" xlink:title="00000054 - Disclosure - SCHEDULE OF INTANGIBLE ASSETS (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaapPatentsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapPatentsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_LicensesMember" xlink:label="loc_HROWLicensesMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_HROWLicensesMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TrademarksMember" xlink:label="loc_us-gaapTrademarksMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapTrademarksMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaapCustomerRelationshipsMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapCustomerRelationshipsMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaapTradeNamesMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapTradeNamesMember_100" xlink:type="arc" order="101" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NonCompetitionClauseMember" xlink:label="loc_HROWNonCompetitionClauseMember_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_HROWNonCompetitionClauseMember_120" xlink:type="arc" order="121" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_StatePharmacyLicensesMember" xlink:label="loc_HROWStatePharmacyLicensesMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_HROWStatePharmacyLicensesMember_150" xlink:type="arc" order="151" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetUsefulLife_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetUsefulLife_190" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsGross_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsGross_190" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_190" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_FiniteLivedIntangibleAssetsImpairment" xlink:label="loc_HROWFiniteLivedIntangibleAssetsImpairment_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_HROWFiniteLivedIntangibleAssetsImpairment_190" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_IntangibleAssetsNetExcludingsGoodwill" xlink:label="loc_HROWIntangibleAssetsNetExcludingsGoodwill_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_HROWIntangibleAssetsNetExcludingsGoodwill_190" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationMethod" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationMethod_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationMethod_190" xlink:type="arc" order="5" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfAmortizationExpensesForIntangibleAssetsDetails" xlink:title="00000055 - Disclosure - SCHEDULE OF AMORTIZATION EXPENSES FOR INTANGIBLE ASSETS (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PatentsMember" xlink:label="loc_us-gaapPatentsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapPatentsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_LicensesMember" xlink:label="loc_HROWLicensesMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_HROWLicensesMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaapCustomerRelationshipsMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapCustomerRelationshipsMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TradeNamesMember" xlink:label="loc_us-gaapTradeNamesMember_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapTradeNamesMember_120" xlink:type="arc" order="121" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_StatePharmacyLicensesMember" xlink:label="loc_HROWStatePharmacyLicensesMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_HROWStatePharmacyLicensesMember_160" xlink:type="arc" order="161" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaapAmortizationOfIntangibleAssets_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapAmortizationOfIntangibleAssets_250" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfEstimatedFutureAmortizationExpenseDetails" xlink:title="00000056 - Disclosure - SCHEDULE OF ESTIMATED FUTURE AMORTIZATION EXPENSE (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/IntangibleAssetsAndGoodwillDetailsNarrative" xlink:title="00000057 - Disclosure - INTANGIBLE ASSETS AND GOODWILL (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfAccountsPayableAndAccruedExpensesDetails" xlink:title="00000058 - Disclosure - SCHEDULE OF ACCOUNTS PAYABLE AND ACCRUED EXPENSES (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SummaryOfFutureMinimumPaymentsDetails" xlink:title="00000059 - Disclosure - SUMMARY OF FUTURE MINIMUM PAYMENTS (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/DebtDetailsNarrative" xlink:title="00000060 - Disclosure - DEBT (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaapDebtInstrumentLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaapDebtInstrumentTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtInstrumentLineItems" xlink:to="loc_us-gaapDebtInstrumentTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDebtInstrumentTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_TermLoanAndSecurityAgreementMember" xlink:label="loc_HROWTermLoanAndSecurityAgreementMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWTermLoanAndSecurityAgreementMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SWKAmendmentMember" xlink:label="loc_HROWSWKAmendmentMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWSWKAmendmentMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_BusinessLoanAgreementMember" xlink:label="loc_HROWBusinessLoanAgreementMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWBusinessLoanAgreementMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDebtInstrumentTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SWKFundingLLCMember" xlink:label="loc_HROWSWKFundingLLCMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWSWKFundingLLCMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaapVariableRateAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDebtInstrumentTable" xlink:to="loc_us-gaapVariableRateAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaapVariableRateDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapVariableRateAxis" xlink:to="loc_us-gaapVariableRateDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaapVariableRateDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapVariableRateAxis" xlink:to="loc_us-gaapVariableRateDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaapLondonInterbankOfferedRateLIBORMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapVariableRateDomain" xlink:to="loc_us-gaapLondonInterbankOfferedRateLIBORMember_20" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_BaseRateMember" xlink:label="loc_us-gaapBaseRateMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapVariableRateDomain" xlink:to="loc_us-gaapBaseRateMember_30" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDebtInstrumentTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_20" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaapDebtInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDebtInstrumentTable" xlink:to="loc_us-gaapDebtInstrumentAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaapDebtInstrumentNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtInstrumentAxis" xlink:to="loc_us-gaapDebtInstrumentNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NotesPayableMember" xlink:label="loc_HROWNotesPayableMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentNameDomain" xlink:to="loc_HROWNotesPayableMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaapDebtInstrumentFaceAmount_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentLineItems" xlink:to="loc_us-gaapDebtInstrumentFaceAmount_120" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentDescriptionOfVariableRateBasis" xlink:label="loc_us-gaapDebtInstrumentDescriptionOfVariableRateBasis_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentLineItems" xlink:to="loc_us-gaapDebtInstrumentDescriptionOfVariableRateBasis_120" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateStatedPercentage_120" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AmortizationOfDebtDiscountPremium" xlink:label="loc_us-gaapAmortizationOfDebtDiscountPremium_120" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtInstrumentLineItems" xlink:to="loc_us-gaapAmortizationOfDebtDiscountPremium_120" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfFutureLeasePaymentUnderOperatingLeasesDetails" xlink:title="00000061 - Disclosure - SCHEDULE OF FUTURE LEASE PAYMENT UNDER OPERATING LEASES (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfFutureLeasePaymentUnderFinanceLeaseDetails" xlink:title="00000062 - Disclosure - SCHEDULE OF FUTURE LEASE PAYMENT UNDER FINANCE LEASE (Details)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/LeasesDetailsNarrative" xlink:title="00000063 - Disclosure - LEASES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionLineItems" xlink:label="loc_us-gaapLesseeLeaseDescriptionLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeLeaseDescriptionTable" xlink:label="loc_us-gaapLesseeLeaseDescriptionTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapLesseeLeaseDescriptionTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srtStatementGeographicalAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLesseeLeaseDescriptionTable" xlink:to="loc_srtStatementGeographicalAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srtSegmentGeographicalDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtStatementGeographicalAxis" xlink:to="loc_srtSegmentGeographicalDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srtSegmentGeographicalDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtStatementGeographicalAxis" xlink:to="loc_srtSegmentGeographicalDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SanDiegoMember" xlink:label="loc_HROWSanDiegoMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtSegmentGeographicalDomain" xlink:to="loc_HROWSanDiegoMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_LedgewoodMember" xlink:label="loc_HROWLedgewoodMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtSegmentGeographicalDomain" xlink:to="loc_HROWLedgewoodMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NashvilleMember" xlink:label="loc_HROWNashvilleMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtSegmentGeographicalDomain" xlink:to="loc_HROWNashvilleMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_IrvineMember" xlink:label="loc_HROWIrvineMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtSegmentGeographicalDomain" xlink:to="loc_HROWIrvineMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseContractualTermAxis" xlink:label="loc_us-gaapLeaseContractualTermAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLesseeLeaseDescriptionTable" xlink:to="loc_us-gaapLeaseContractualTermAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseContractualTermDomain" xlink:label="loc_us-gaapLeaseContractualTermDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapLeaseContractualTermAxis" xlink:to="loc_us-gaapLeaseContractualTermDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LeaseContractualTermDomain" xlink:label="loc_us-gaapLeaseContractualTermDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLeaseContractualTermAxis" xlink:to="loc_us-gaapLeaseContractualTermDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_AdditionalSquareFootageOfLeaseMember" xlink:label="loc_HROWAdditionalSquareFootageOfLeaseMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLeaseContractualTermDomain" xlink:to="loc_HROWAdditionalSquareFootageOfLeaseMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AreaOfLand" xlink:label="loc_us-gaapAreaOfLand_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapAreaOfLand_130" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_LeaseExpirationDateDescription" xlink:label="loc_HROWLeaseExpirationDateDescription_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_HROWLeaseExpirationDateDescription_130" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_LesseeOperatingLeaseDescription" xlink:label="loc_us-gaapLesseeOperatingLeaseDescription_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapLesseeOperatingLeaseDescription_130" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaapOtherNonoperatingIncomeExpense_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapOtherNonoperatingIncomeExpense_130" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_OperatingLeaseWeightedAverageIncrementalBorrowingRate" xlink:label="loc_HROWOperatingLeaseWeightedAverageIncrementalBorrowingRate_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_HROWOperatingLeaseWeightedAverageIncrementalBorrowingRate_130" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="loc_us-gaapOperatingLeaseWeightedAverageRemainingLeaseTerm1_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapOperatingLeaseWeightedAverageRemainingLeaseTerm1_130" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_CashPaidInOperatingLeaseLiability" xlink:label="loc_HROWCashPaidInOperatingLeaseLiability_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_HROWCashPaidInOperatingLeaseLiability_130" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeaseExpense" xlink:label="loc_us-gaapOperatingLeaseExpense_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapOperatingLeaseExpense_130" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_FinanceLeaseWeightedAverageIncrementalBorrowingRate" xlink:label="loc_HROWFinanceLeaseWeightedAverageIncrementalBorrowingRate_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_HROWFinanceLeaseWeightedAverageIncrementalBorrowingRate_130" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseWeightedAverageRemainingLeaseTerm1" xlink:label="loc_us-gaapFinanceLeaseWeightedAverageRemainingLeaseTerm1_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapFinanceLeaseWeightedAverageRemainingLeaseTerm1_130" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingLeasesIncomeStatementDepreciationExpenseOnPropertySubjectToOrHeldForLease" xlink:label="loc_us-gaapOperatingLeasesIncomeStatementDepreciationExpenseOnPropertySubjectToOrHeldForLease_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapOperatingLeasesIncomeStatementDepreciationExpenseOnPropertySubjectToOrHeldForLease_130" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_FinanceLeaseInterestExpense" xlink:label="loc_us-gaapFinanceLeaseInterestExpense_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLesseeLeaseDescriptionLineItems" xlink:to="loc_us-gaapFinanceLeaseInterestExpense_130" xlink:type="arc" order="11" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfStockOptionPlanActivityDetails" xlink:title="00000064 - Disclosure - SCHEDULE OF STOCK OPTION PLAN ACTIVITY (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_StockOptionPlanOneMember" xlink:label="loc_HROWStockOptionPlanOneMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_HROWStockOptionPlanOneMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_40" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesStockOptionsExercised_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesStockOptionsExercised_40" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_40" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod_40" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice_40" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_40" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_40" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_40" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_40" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_40" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_40" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_40" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_40" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_40" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_40" xlink:type="arc" order="19" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfFairValueAssumptionsDetails" xlink:title="00000065 - Disclosure - SCHEDULE OF FAIR VALUE ASSUMPTIONS (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_OptionsEmployeesMember" xlink:label="loc_HROWOptionsEmployeesMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_HROWOptionsEmployeesMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMinimum_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRateMaximum_40" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMinimum_40" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRateMaximum_40" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_40" xlink:type="arc" order="6" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfStockOptionOutstandingAndExercisableDetails" xlink:title="00000066 - Disclosure - SCHEDULE OF STOCK OPTION OUTSTANDING AND EXERCISABLE (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:label="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:label="loc_us-gaapScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaapScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:label="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeTable" xlink:to="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:to="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:label="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis" xlink:to="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RangeOneMember" xlink:label="loc_HROWRangeOneMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_HROWRangeOneMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RangeTwoMember" xlink:label="loc_HROWRangeTwoMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_HROWRangeTwoMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RangeThreeMember" xlink:label="loc_HROWRangeThreeMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_HROWRangeThreeMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RangeFourMember" xlink:label="loc_HROWRangeFourMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain" xlink:to="loc_HROWRangeFourMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit" xlink:label="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit_110" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit" xlink:label="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit_110" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions" xlink:label="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions_110" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaapSharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaapSharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageRemainingContractualTerm2_110" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1" xlink:label="loc_us-gaapSharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaapSharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1_110" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions" xlink:label="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions_110" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1" xlink:label="loc_us-gaapSharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLineItems" xlink:to="loc_us-gaapSharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1_110" xlink:type="arc" order="6" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfRestrictedStockUnitsActivityDetails" xlink:title="00000067 - Disclosure - SCHEDULE OF RESTRICTED STOCK UNITS ACTIVITY (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaapRestrictedStockUnitsRSUMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaapRestrictedStockUnitsRSUMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_40" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_40" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_40" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_40" xlink:type="arc" order="6" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfWarrantsActivityDetails" xlink:title="00000068 - Disclosure - SCHEDULE OF WARRANTS ACTIVITY (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightLineItems" xlink:label="loc_us-gaapClassOfWarrantOrRightLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightTable" xlink:label="loc_us-gaapClassOfWarrantOrRightTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaapClassOfWarrantOrRightAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapClassOfWarrantOrRightTable" xlink:to="loc_us-gaapClassOfWarrantOrRightAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaapClassOfWarrantOrRightDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapClassOfWarrantOrRightAxis" xlink:to="loc_us-gaapClassOfWarrantOrRightDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaapClassOfWarrantOrRightDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapClassOfWarrantOrRightAxis" xlink:to="loc_us-gaapClassOfWarrantOrRightDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaapWarrantMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightDomain" xlink:to="loc_us-gaapWarrantMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingNumber_40" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingWeightedAverageExercisePrice1" xlink:label="loc_HROWShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingWeightedAverageExercisePrice1_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_HROWShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingWeightedAverageExercisePrice1_40" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted_40" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExercised_40" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpirations" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpirations_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsExpirations_40" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingAndExercisableNumber" xlink:label="loc_HROWShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingAndExercisableNumber_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_HROWShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingAndExercisableNumber_40" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingAndExercisableWeightedAverageExercisePrice1" xlink:label="loc_HROWShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingAndExercisableWeightedAverageExercisePrice1_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_HROWShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionsEquityInstrumentsOutstandingAndExercisableWeightedAverageExercisePrice1_40" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SharebasedCompensationArrangementBySharebasedPaymentAwardNonOptionsEquityInstrumentOutstandingWeightedAverageRemainingContractualTerm1" xlink:label="loc_HROWSharebasedCompensationArrangementBySharebasedPaymentAwardNonOptionsEquityInstrumentOutstandingWeightedAverageRemainingContractualTerm1_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_HROWSharebasedCompensationArrangementBySharebasedPaymentAwardNonOptionsEquityInstrumentOutstandingWeightedAverageRemainingContractualTerm1_40" xlink:type="arc" order="7" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfWarrantsOutstandingAndWarrantsExercisableDetails" xlink:title="00000069 - Disclosure - SCHEDULE OF WARRANTS OUTSTANDING AND WARRANTS EXERCISABLE (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightLineItems" xlink:label="loc_us-gaapClassOfWarrantOrRightLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightTable" xlink:label="loc_us-gaapClassOfWarrantOrRightTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapClassOfWarrantOrRightTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_LenderWarrantsMember" xlink:label="loc_HROWLenderWarrantsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWLenderWarrantsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SettlementWarrantsMember" xlink:label="loc_HROWSettlementWarrantsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWSettlementWarrantsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_LenderWarrantsOneMember" xlink:label="loc_HROWLenderWarrantsOneMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWLenderWarrantsOneMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaapClassOfWarrantOrRightAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapClassOfWarrantOrRightTable" xlink:to="loc_us-gaapClassOfWarrantOrRightAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaapClassOfWarrantOrRightDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapClassOfWarrantOrRightAxis" xlink:to="loc_us-gaapClassOfWarrantOrRightDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaapClassOfWarrantOrRightDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapClassOfWarrantOrRightAxis" xlink:to="loc_us-gaapClassOfWarrantOrRightDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_WarrantMember" xlink:label="loc_us-gaapWarrantMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightDomain" xlink:to="loc_us-gaapWarrantMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_WarrantsIssuanceDate" xlink:label="loc_HROWWarrantsIssuanceDate_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_HROWWarrantsIssuanceDate_80" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightOutstanding" xlink:label="loc_us-gaapClassOfWarrantOrRightOutstanding_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightOutstanding_80" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_80" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_WarrantsAndRightsOutstandingMaturityDates" xlink:label="loc_HROWWarrantsAndRightsOutstandingMaturityDates_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightLineItems" xlink:to="loc_HROWWarrantsAndRightsOutstandingMaturityDates_80" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfStockBasedCompensationGrantedToEmployeesDirectorsConsultantsDetails" xlink:title="00000070 - Disclosure - SCHEDULE OF STOCK BASED COMPENSATION GRANTED TO EMPLOYEES DIRECTORS CONSULTANTS (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualPostretirementBenefitsLineItems" xlink:label="loc_us-gaapDeferredCompensationArrangementWithIndividualPostretirementBenefitsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable" xlink:label="loc_us-gaapScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDeferredCompensationArrangementWithIndividualPostretirementBenefitsLineItems" xlink:to="loc_us-gaapScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_EmployeesMember" xlink:label="loc_HROWEmployeesMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWEmployeesMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_DirectorMember" xlink:label="loc_srtDirectorMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_srtDirectorMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ConsultantMember" xlink:label="loc_HROWConsultantMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWConsultantMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaapIncomeStatementLocationAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfDeferredCompensationArrangementWithIndividualExcludingShareBasedPaymentsAndPostretirementBenefitsByTitleOfIndividualAndByTypeOfDeferredCompensationTable" xlink:to="loc_us-gaapIncomeStatementLocationAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaapIncomeStatementLocationDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapIncomeStatementLocationAxis" xlink:to="loc_us-gaapIncomeStatementLocationDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaapIncomeStatementLocationDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapIncomeStatementLocationAxis" xlink:to="loc_us-gaapIncomeStatementLocationDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SellingGeneralAndAdministrativeMember" xlink:label="loc_HROWSellingGeneralAndAdministrativeMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementLocationDomain" xlink:to="loc_HROWSellingGeneralAndAdministrativeMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaapAllocatedShareBasedCompensationExpense_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDeferredCompensationArrangementWithIndividualPostretirementBenefitsLineItems" xlink:to="loc_us-gaapAllocatedShareBasedCompensationExpense_170" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/StockholdersEquityAndStock-basedCompensationDetailsNarrative" xlink:title="00000071 - Disclosure - STOCKHOLDERS&#8217; EQUITY AND STOCK-BASED COMPENSATION (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable" xlink:label="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaapRestrictedStockUnitsRSUMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaapRestrictedStockUnitsRSUMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_StockOptionPlanMember" xlink:label="loc_HROWStockOptionPlanMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_HROWStockOptionPlanMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RestrictedStockUnitsRSUOneMember" xlink:label="loc_HROWRestrictedStockUnitsRSUOneMember_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_HROWRestrictedStockUnitsRSUOneMember_170" xlink:type="arc" order="171" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_UnvestedRSUMember" xlink:label="loc_HROWUnvestedRSUMember_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_HROWUnvestedRSUMember_210" xlink:type="arc" order="211" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RestrictedStockMember" xlink:label="loc_us-gaapRestrictedStockMember_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaapRestrictedStockMember_250" xlink:type="arc" order="252" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_CommonStockOneMember" xlink:label="loc_HROWCommonStockOneMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_HROWCommonStockOneMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_30" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_40" xlink:type="arc" order="42" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_DirectorMember" xlink:label="loc_srtDirectorMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_srtDirectorMember_60" xlink:type="arc" order="62" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_EmployeesAndConsultantMember" xlink:label="loc_HROWEmployeesAndConsultantMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWEmployeesAndConsultantMember_90" xlink:type="arc" order="92" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_BoardOfDirectorsMember" xlink:label="loc_HROWBoardOfDirectorsMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWBoardOfDirectorsMember_160" xlink:type="arc" order="162" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NewMemberOfBoardOfDirectorsMember" xlink:label="loc_HROWNewMemberOfBoardOfDirectorsMember_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWNewMemberOfBoardOfDirectorsMember_170" xlink:type="arc" order="172" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NewMemberOfBoardOfDirectorsOneMember" xlink:label="loc_HROWNewMemberOfBoardOfDirectorsOneMember_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWNewMemberOfBoardOfDirectorsOneMember_180" xlink:type="arc" order="182" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ConsultantMember" xlink:label="loc_HROWConsultantMember_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWConsultantMember_270" xlink:type="arc" order="273" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaapPlanNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapPlanNameAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_TwoThousandAndSeventeenIncentiveStockandAwardsPlanMember" xlink:label="loc_HROWTwoThousandAndSeventeenIncentiveStockandAwardsPlanMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_HROWTwoThousandAndSeventeenIncentiveStockandAwardsPlanMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_BaumPerformanceOptionMember" xlink:label="loc_HROWBaumPerformanceOptionMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWBaumPerformanceOptionMember_100" xlink:type="arc" order="101" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MayfieldPharmaceuticalsIncMember" xlink:label="loc_HROWMayfieldPharmaceuticalsIncMember_240" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_HROWMayfieldPharmaceuticalsIncMember_240" xlink:type="arc" order="241" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2020/dei-2020-01-31.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_EllePharmaceuticalLLCMember" xlink:label="loc_HROWEllePharmaceuticalLLCMember_240" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_HROWEllePharmaceuticalLLCMember_240" xlink:type="arc" order="242" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesRestrictedStockAwardGross_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesRestrictedStockAwardGross_290" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueRestrictedStockAwardGross_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueRestrictedStockAwardGross_290" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NumberOfCommonStockIssuedOnCashlessExercise" xlink:label="loc_HROWNumberOfCommonStockIssuedOnCashlessExercise_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_HROWNumberOfCommonStockIssuedOnCashlessExercise_290" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_290" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_290" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_CommonStockWithheldForPayrollTaxWithholdingsShare" xlink:label="loc_HROWCommonStockWithheldForPayrollTaxWithholdingsShare_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_HROWCommonStockWithheldForPayrollTaxWithholdingsShare_290" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_CommonStockWithheldForPayrollTaxWithholdingsValue" xlink:label="loc_HROWCommonStockWithheldForPayrollTaxWithholdingsValue_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_HROWCommonStockWithheldForPayrollTaxWithholdingsValue_290" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RestrictedStockUnitsVested" xlink:label="loc_HROWRestrictedStockUnitsVested_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_HROWRestrictedStockUnitsVested_290" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_290" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_290" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ClosingPriceOfCommonStockPricePerShare" xlink:label="loc_HROWClosingPriceOfCommonStockPricePerShare_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_HROWClosingPriceOfCommonStockPricePerShare_290" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_290" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationDescriptionAndTerms" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationDescriptionAndTerms_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationDescriptionAndTerms_290" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_AverageStockPrice" xlink:label="loc_HROWAverageStockPrice_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_HROWAverageStockPrice_290" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_290" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_290" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_290" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_290" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ForfeitureFactorPercentage" xlink:label="loc_HROWForfeitureFactorPercentage_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_HROWForfeitureFactorPercentage_290" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_290" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_290" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ShareBasedCompensation" xlink:label="loc_us-gaapShareBasedCompensation_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapShareBasedCompensation_290" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_290" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_AggregatePurchasePrice" xlink:label="loc_HROWAggregatePurchasePrice_290" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAccumulatedOtherComprehensiveIncomeLossLineItems" xlink:to="loc_HROWAggregatePurchasePrice_290" xlink:type="arc" order="23" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/CommitmentsAndContingenciesDetailsNarrative" xlink:title="00000072 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:label="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:label="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_KlarityLicenseAgreementMember" xlink:label="loc_HROWKlarityLicenseAgreementMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWKlarityLicenseAgreementMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_LicenseAgreementMember" xlink:label="loc_HROWLicenseAgreementMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWLicenseAgreementMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_InjectableAssetPurchaseAgreementMember" xlink:label="loc_HROWInjectableAssetPurchaseAgreementMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWInjectableAssetPurchaseAgreementMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_DexycuAgreementMember" xlink:label="loc_HROWDexycuAgreementMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWDexycuAgreementMember_110" xlink:type="arc" order="111" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SalesAndMarketingAgreementsMember" xlink:label="loc_HROWSalesAndMarketingAgreementsMember_140" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWSalesAndMarketingAgreementsMember_140" xlink:type="arc" order="141" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_AssetPurchaseLicenseAndRelatedAgreementsMember" xlink:label="loc_HROWAssetPurchaseLicenseAndRelatedAgreementsMember_160" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_HROWAssetPurchaseLicenseAndRelatedAgreementsMember_160" xlink:type="arc" order="161" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RichardLLindstromMDMember" xlink:label="loc_HROWRichardLLindstromMDMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_HROWRichardLLindstromMDMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_StatementScenarioAxis" xlink:label="loc_srtStatementScenarioAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_srtStatementScenarioAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="loc_srtScenarioUnspecifiedDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtStatementScenarioAxis" xlink:to="loc_srtScenarioUnspecifiedDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ScenarioUnspecifiedDomain" xlink:label="loc_srtScenarioUnspecifiedDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtStatementScenarioAxis" xlink:to="loc_srtScenarioUnspecifiedDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_InitialPaymentMember" xlink:label="loc_HROWInitialPaymentMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtScenarioUnspecifiedDomain" xlink:to="loc_HROWInitialPaymentMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SecondPaymentMember" xlink:label="loc_HROWSecondPaymentMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtScenarioUnspecifiedDomain" xlink:to="loc_HROWSecondPaymentMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_FinalPaymentMember" xlink:label="loc_HROWFinalPaymentMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtScenarioUnspecifiedDomain" xlink:to="loc_HROWFinalPaymentMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_RoyaltyPaymentDescription" xlink:label="loc_HROWRoyaltyPaymentDescription_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_HROWRoyaltyPaymentDescription_230" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RoyaltyExpense" xlink:label="loc_us-gaapRoyaltyExpense_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapRoyaltyExpense_230" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NetSalesRevenue" xlink:label="loc_HROWNetSalesRevenue_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_HROWNetSalesRevenue_230" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_MilestonePaymentInCash" xlink:label="loc_HROWMilestonePaymentInCash_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_HROWMilestonePaymentInCash_230" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_AgreeementExpirationDescription" xlink:label="loc_HROWAgreeementExpirationDescription_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_HROWAgreeementExpirationDescription_230" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SalesCommissionsAndFees" xlink:label="loc_us-gaapSalesCommissionsAndFees_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapSalesCommissionsAndFees_230" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaapAllocatedShareBasedCompensationExpense_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapAllocatedShareBasedCompensationExpense_230" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AccountsPayableCurrentAndNoncurrent" xlink:label="loc_us-gaapAccountsPayableCurrentAndNoncurrent_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapAccountsPayableCurrentAndNoncurrent_230" xlink:type="arc" order="7" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/ScheduleOfSegmentNetRevenuesSegmentOperatingExpensesAndSegmentContributionDetails" xlink:title="00000073 - Disclosure - SCHEDULE OF SEGMENT NET REVENUES, SEGMENT OPERATING EXPENSES AND SEGMENT CONTRIBUTION (Details)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaapSegmentReportingInformationLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srtConsolidationItemsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="loc_srtConsolidationItemsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srtConsolidationItemsDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtConsolidationItemsAxis" xlink:to="loc_srtConsolidationItemsDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/srt/2020/elts/srt-2020-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srtConsolidationItemsDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtConsolidationItemsAxis" xlink:to="loc_srtConsolidationItemsDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaapOperatingSegmentsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtConsolidationItemsDomain" xlink:to="loc_us-gaapOperatingSegmentsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaapCorporateNonSegmentMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtConsolidationItemsDomain" xlink:to="loc_us-gaapCorporateNonSegmentMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaapStatementBusinessSegmentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="loc_us-gaapStatementBusinessSegmentsAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaapSegmentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementBusinessSegmentsAxis" xlink:to="loc_us-gaapSegmentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaapSegmentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementBusinessSegmentsAxis" xlink:to="loc_us-gaapSegmentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_PharmaceuticalCompoundingMember" xlink:label="loc_HROWPharmaceuticalCompoundingMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentDomain" xlink:to="loc_HROWPharmaceuticalCompoundingMember_0" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_PharmaceuticalDrugDevelopmentMember" xlink:label="loc_HROWPharmaceuticalDrugDevelopmentMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentDomain" xlink:to="loc_HROWPharmaceuticalDrugDevelopmentMember_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaapIncomeStatementLocationAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="loc_us-gaapIncomeStatementLocationAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaapIncomeStatementLocationDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapIncomeStatementLocationAxis" xlink:to="loc_us-gaapIncomeStatementLocationDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaapIncomeStatementLocationDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapIncomeStatementLocationAxis" xlink:to="loc_us-gaapIncomeStatementLocationDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpenseMember" xlink:label="loc_us-gaapResearchAndDevelopmentExpenseMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementLocationDomain" xlink:to="loc_us-gaapResearchAndDevelopmentExpenseMember_40" xlink:type="arc" order="42" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapRevenueFromContractWithCustomerExcludingAssessedTax_210" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="loc_us-gaapCostOfGoodsAndServicesSold_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapCostOfGoodsAndServicesSold_210" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaapGrossProfit_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapGrossProfit_210" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SellingGeneralAndAdministrativeExpense" xlink:label="loc_us-gaapSellingGeneralAndAdministrativeExpense_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapSellingGeneralAndAdministrativeExpense_210" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaapResearchAndDevelopmentExpense_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapResearchAndDevelopmentExpense_210" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_SegmentContribution" xlink:label="loc_HROWSegmentContribution_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_HROWSegmentContribution_210" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapOperatingIncomeLoss_210" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_AdjustmentForAmortization" xlink:label="loc_us-gaapAdjustmentForAmortization_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapAdjustmentForAmortization_210" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ImpairmentAndDisposalOfLonglivedAssets" xlink:label="loc_HROWImpairmentAndDisposalOfLonglivedAssets_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_HROWImpairmentAndDisposalOfLonglivedAssets_210" xlink:type="arc" order="8" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SegmentInformationAndConcentrationsDetailsNarrative" xlink:title="00000074 - Disclosure - SEGMENT INFORMATION AND CONCENTRATIONS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems" xlink:label="loc_us-gaapEntityWideRevenueMajorCustomerLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:label="loc_us-gaapScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapEntityWideRevenueMajorCustomerLineItems" xlink:to="loc_us-gaapScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaapConcentrationRiskByTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:to="loc_us-gaapConcentrationRiskByTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaapConcentrationRiskTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapConcentrationRiskByTypeAxis" xlink:to="loc_us-gaapConcentrationRiskTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaapConcentrationRiskTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapConcentrationRiskByTypeAxis" xlink:to="loc_us-gaapConcentrationRiskTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_ThreeMainSuppliersMember" xlink:label="loc_HROWThreeMainSuppliersMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskTypeDomain" xlink:to="loc_HROWThreeMainSuppliersMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="hrow-20200930.xsd#HROW_NumberOfOperatingSegmentsDescription" xlink:label="loc_HROWNumberOfOperatingSegmentsDescription_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEntityWideRevenueMajorCustomerLineItems" xlink:to="loc_HROWNumberOfOperatingSegmentsDescription_100" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaapConcentrationRiskPercentage1_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEntityWideRevenueMajorCustomerLineItems" xlink:to="loc_us-gaapConcentrationRiskPercentage1_100" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://harrowinc.com/role/SubsequentEventsDetailsNarrative" xlink:title="00000075 - Disclosure - SUBSEQUENT EVENTS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaapSubsequentEventLineItems" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTable" xlink:label="loc_us-gaapSubsequentEventTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapSubsequentEventTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaapSubsequentEventTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapSubsequentEventTable" xlink:to="loc_us-gaapSubsequentEventTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaapSubsequentEventTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsequentEventTypeAxis" xlink:to="loc_us-gaapSubsequentEventTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaapSubsequentEventMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventTypeDomain" xlink:to="loc_us-gaapSubsequentEventMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="http://xbrl.fasb.org/us-gaap/2020/elts/us-gaap-2020-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsequentEventLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_20" xlink:type="arc" order="0" />
    </link:definitionLink>
</link:linkbase>
