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  <xsd:element id="algn_EffectiveIncomeTaxRateReconciliationTaxCutsandJobsActof2017" name="EffectiveIncomeTaxRateReconciliationTaxCutsandJobsActof2017" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_EffectiveIncomeTaxRateReconciliationValuationAllowanceReleaseForForeignCountry" name="EffectiveIncomeTaxRateReconciliationValuationAllowanceReleaseForForeignCountry" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_Effectiveincometaxrateimpactonexpirationofstatuteoflimitations" name="Effectiveincometaxrateimpactonexpirationofstatuteoflimitations" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_EmployeeStockIncentivePlan2005Member" name="EmployeeStockIncentivePlan2005Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_EmployeeStockPurchasePlan2010Member" name="EmployeeStockPurchasePlan2010Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_EmployeeStockPurchasePlanDurationOfOfferingPeriod" name="EmployeeStockPurchasePlanDurationOfOfferingPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_EmployeeStockPurchasePlanMember" name="EmployeeStockPurchasePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_EmployeeStockPurchasePlanNumberOfSharesAvailableForIssuance" name="EmployeeStockPurchasePlanNumberOfSharesAvailableForIssuance" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_EmployeeStockPurchasePlanNumberOfSixMonthPurchasingPeriods" name="EmployeeStockPurchasePlanNumberOfSixMonthPurchasingPeriods" nillable="true" substitutionGroup="xbrli:item" type="xbrli:decimalItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_EquityMethodInvestmentOwnershipAcquired" name="EquityMethodInvestmentOwnershipAcquired" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="algn_ExcessTaxChargeBenefitFromShareBasedCompensationOperatingActivities" name="ExcessTaxChargeBenefitFromShareBasedCompensationOperatingActivities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_ExistingTechnologyMember" name="ExistingTechnologyMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisLineItems" name="FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTable" name="FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_FiniteLivedIntangibleAssetsAccumulatedImpairmentLoss" name="FiniteLivedIntangibleAssetsAccumulatedImpairmentLoss" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="algn_IncomeTaxesLineItems" name="IncomeTaxesLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_IncomeTaxesTable" name="IncomeTaxesTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_InvisalignExpressliteMember" name="InvisalignExpressliteMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_InvisalignFullMember" name="InvisalignFullMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_IsraeliSeveranceFundsMember" name="IsraeliSeveranceFundsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_Lawsuitagainst3ShapeASMember" name="Lawsuitagainst3ShapeASMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_LawsuitsAgainstExecutiveOfficers" name="LawsuitsAgainstExecutiveOfficers" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="algn_LeaseTerm" name="LeaseTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_LoansAndLeasesReceivableAgreedUponRelatedParties" name="LoansAndLeasesReceivableAgreedUponRelatedParties" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <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 abstract="true" id="algn_MarketableSecuritiesAndFairValueMeasurementsAbstract" name="MarketableSecuritiesAndFairValueMeasurementsAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" 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_May2018RepurchaseMember" name="May2018RepurchaseMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_MonthlyVestingMember" name="MonthlyVestingMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_MunicipalSecuritiesMember" name="MunicipalSecuritiesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_NationalCorporateTaxRate" name="NationalCorporateTaxRate" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" 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_NumberofDerivativeLawsuits" name="NumberofDerivativeLawsuits" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <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 id="algn_PatentInfringementNumberofLawsuits" name="PatentInfringementNumberofLawsuits" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_PatentInfringementby3ShapeMember" name="PatentInfringementby3ShapeMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" 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_PurchaseAndSaleAgreementCashPaid" name="PurchaseAndSaleAgreementCashPaid" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="algn_PurchaseAndSaleAgreementCashToBePaid" name="PurchaseAndSaleAgreementCashToBePaid" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="algn_PurchaseAndSaleAgreementPurchasePrice" name="PurchaseAndSaleAgreementPurchasePrice" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <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_SECSchedule1209ValuationAllowancesSalesReturnsMember" name="SECSchedule1209ValuationAllowancesSalesReturnsMember" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitsInPeriodWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitsInPeriodWeightedAverageGrantDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedTotalIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedTotalIntrinsicValue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedTotalIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedTotalIntrinsicValue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMethodUsedTableTextBlock" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsMethodUsedTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" 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_ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePricePercentageOfFairMarketValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardPurchasePricePercentageOfFairMarketValue" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesRemainingAvailableForIssuance" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesRemainingAvailableForIssuance" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element id="algn_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentage" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <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 id="algn_ShareRepurchasesPricePaidPerShare" name="ShareRepurchasesPricePaidPerShare" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" 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 id="algn_SharebasedCompensationArrangementbySharebasedPaymentAwardWeightOfAwardedSharesAgainstAuthorizedMaximum" name="SharebasedCompensationArrangementbySharebasedPaymentAwardWeightOfAwardedSharesAgainstAuthorizedMaximum" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="algn_SignificantAccountingPoliciesLineItems" name="SignificantAccountingPoliciesLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_SignificantAccountingPoliciesTable" name="SignificantAccountingPoliciesTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_StandardProductWarrantyTimePeriod" name="StandardProductWarrantyTimePeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" 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 abstract="true" id="algn_StockPlan2001Member" name="StockPlan2001Member" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_StockholderRightsPlanMember" name="StockholderRightsPlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_StockholdersEquityNoteLineItems" name="StockholdersEquityNoteLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_StockholdersEquityNoteTable" name="StockholdersEquityNoteTable" nillable="true" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType" 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 id="algn_TaxCutsandJobsActof2017IncompleteAccountingUndistributedAccumulatedEarningsofForeignSubsidiaryProvisionalUnrecognizedDeferredTaxAsset" name="TaxCutsandJobsActof2017IncompleteAccountingUndistributedAccumulatedEarningsofForeignSubsidiaryProvisionalUnrecognizedDeferredTaxAsset" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="algn_TaxCutsandJobsActof2017IncompleteAccountingUndistributedAccumulatedEarningsofForeignSubsidiaryProvisionalUnrecognizedDeferredTaxLiability" name="TaxCutsandJobsActof2017IncompleteAccountingUndistributedAccumulatedEarningsofForeignSubsidiaryProvisionalUnrecognizedDeferredTaxLiability" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="algn_TaxWithholdingRelatedToVestingOfRestrictedStockUnits" name="TaxWithholdingRelatedToVestingOfRestrictedStockUnits" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="algn_U.S.GovernmentTreasuryBondsMember" name="U.S.GovernmentTreasuryBondsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="algn_ValuationAllowancesAndReservesChargedToCostAndExpenseOrRevenue" name="ValuationAllowancesAndReservesChargedToCostAndExpenseOrRevenue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" 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>





