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  <xsd:element abstract="true" id="algn_LongTermInvestmentsMember" name="LongTermInvestmentsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_MarketPerformanceBasedRestrictedStockUnitsMember" name="MarketPerformanceBasedRestrictedStockUnitsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_MarketableSecuritiesWeightedAverageRemainingMaturity" name="MarketableSecuritiesWeightedAverageRemainingMaturity" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_MaturityPeriodUsedToClassifyInvestments" name="MaturityPeriodUsedToClassifyInvestments" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_NotesToFinancialStatementsAbstract" name="NotesToFinancialStatementsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_OperatingLeasesFutureMinimumPaymentsDueRemainderOfPeriod" name="OperatingLeasesFutureMinimumPaymentsDueRemainderOfPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="algn_OtherInternationalMember" name="OtherInternationalMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_OtherLongtermAssets" name="OtherLongtermAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="algn_PatentInfringementBy3ShapeMember" name="PatentInfringementBy3ShapeMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_PatentInfringementNumberOfLawsuits" name="PatentInfringementNumberOfLawsuits" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_PercentageOfMarketPerformanceBasedRestrictedStockUnitsDuringVestingPeriod" name="PercentageOfMarketPerformanceBasedRestrictedStockUnitsDuringVestingPeriod" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_RecentAccountingPronouncementsPolicyTextBlock" name="RecentAccountingPronouncementsPolicyTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_RevenueInitialApplicationPeriodCumulativeEffectTransitionLineItems" name="RevenueInitialApplicationPeriodCumulativeEffectTransitionLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_RevenueInitialApplicationPeriodCumulativeEffectTransitionTable" name="RevenueInitialApplicationPeriodCumulativeEffectTransitionTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_RevenueRemainingPerformanceObligation" name="RevenueRemainingPerformanceObligation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="algn_SDCMember" name="SDCMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_ScannersAndServicesMember" name="ScannersAndServicesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAxis" name="ScheduleOfShareBasedCompensationArrangementByShareBasedPaymentAwardAxis" nillable="true" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerm1" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerm1" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAggregateIntrinsicValueAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsWeightedAverageRemainingContractualTermAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesRemainingAvailableForIssuance" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesRemainingAvailableForIssuance" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="algn_ShareBasedCompensationArrangementsByShareBasedPaymentAwardDomain" name="ShareBasedCompensationArrangementsByShareBasedPaymentAwardDomain" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_ShareRepurchaseProgramDisclosureTextBlock" name="ShareRepurchaseProgramDisclosureTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_ShareRepurchasesLineItems" name="ShareRepurchasesLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_ShareRepurchasesTable" name="ShareRepurchasesTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriodWeightedAverageGrantDateFairValue" name="SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriodWeightedAverageGrantDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_StockIncentivePlan2005Member" name="StockIncentivePlan2005Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit" name="TaxCutsAndJobsActOf2017ChangeInTaxRateIncomeTaxExpenseBenefit" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_ViolationOfTradeLaws3ShapeMember" name="ViolationOfTradeLaws3ShapeMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
</xsd:schema>