<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:b15ba505-21d6-4cbd-ac49-259c921a3a90,g:e45dead9-1309-4701-aea4-047fecdb79f3-->
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:prlb="http://www.protolabs.com/20240930" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:dtr-types1="http://www.xbrl.org/dtr/type/2020-01-21" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" attributeFormDefault="unqualified" elementFormDefault="qualified" targetNamespace="http://www.protolabs.com/20240930">
  <xs:import namespace="http://fasb.org/srt/2024" schemaLocation="https://xbrl.fasb.org/srt/2024/elts/srt-2024.xsd"/>
  <xs:import namespace="http://fasb.org/us-gaap/2024" schemaLocation="https://xbrl.fasb.org/us-gaap/2024/elts/us-gaap-2024.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/instance" schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/2003/linkbase" schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2020-01-21" schemaLocation="https://www.xbrl.org/dtr/type/2020-01-21/types.xsd"/>
  <xs:import namespace="http://www.xbrl.org/dtr/type/2022-03-31" schemaLocation="https://www.xbrl.org/dtr/type/2022-03-31/types.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/country/2024" schemaLocation="https://xbrl.sec.gov/country/2024/country-2024.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/dei/2024" schemaLocation="https://xbrl.sec.gov/dei/2024/dei-2024.xsd"/>
  <xs:import namespace="http://xbrl.sec.gov/ecd/2024" schemaLocation="https://xbrl.sec.gov/ecd/2024/ecd-2024.xsd"/>
  <xs:annotation>
    <xs:appinfo>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="prlb-20240930_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="prlb-20240930_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="prlb-20240930_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:type="simple"/>
      <link:linkbaseRef xmlns:xlink="http://www.w3.org/1999/xlink" xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="prlb-20240930_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:type="simple"/>
      <link:roleType id="Cover" roleURI="http://www.protolabs.com/role/Cover">
        <link:definition>0000001 - Document - Cover</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedBalanceSheets" roleURI="http://www.protolabs.com/role/ConsolidatedBalanceSheets">
        <link:definition>9952151 - Statement - Consolidated Balance Sheets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedBalanceSheetsParenthetical" roleURI="http://www.protolabs.com/role/ConsolidatedBalanceSheetsParenthetical">
        <link:definition>9952152 - Statement - Consolidated Balance Sheets (Parenthetical)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofComprehensiveIncome" roleURI="http://www.protolabs.com/role/ConsolidatedStatementsofComprehensiveIncome">
        <link:definition>9952153 - Statement - Consolidated Statements of Comprehensive Income</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofShareholdersEquity" roleURI="http://www.protolabs.com/role/ConsolidatedStatementsofShareholdersEquity">
        <link:definition>9952154 - Statement - Consolidated Statements of Shareholders' Equity</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="ConsolidatedStatementsofCashFlows" roleURI="http://www.protolabs.com/role/ConsolidatedStatementsofCashFlows">
        <link:definition>9952155 - Statement - Consolidated Statements of Cash Flows</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="BasisofPresentation" roleURI="http://www.protolabs.com/role/BasisofPresentation">
        <link:definition>9952156 - Disclosure - Basis of Presentation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="RecentAccountingPronouncements" roleURI="http://www.protolabs.com/role/RecentAccountingPronouncements">
        <link:definition>9952157 - Disclosure - Recent Accounting Pronouncements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomeperCommonShare" roleURI="http://www.protolabs.com/role/NetIncomeperCommonShare">
        <link:definition>9952158 - Disclosure - Net Income per Common Share</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssets" roleURI="http://www.protolabs.com/role/GoodwillandOtherIntangibleAssets">
        <link:definition>9952159 - Disclosure - Goodwill and Other Intangible Assets</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurements" roleURI="http://www.protolabs.com/role/FairValueMeasurements">
        <link:definition>9952160 - Disclosure - Fair Value Measurements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecurities" roleURI="http://www.protolabs.com/role/MarketableSecurities">
        <link:definition>9952161 - Disclosure - Marketable Securities</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="Inventory" roleURI="http://www.protolabs.com/role/Inventory">
        <link:definition>9952162 - Disclosure - Inventory</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockBasedCompensation" roleURI="http://www.protolabs.com/role/StockBasedCompensation">
        <link:definition>9952163 - Disclosure - Stock-Based Compensation</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveIncomeLoss" roleURI="http://www.protolabs.com/role/AccumulatedOtherComprehensiveIncomeLoss">
        <link:definition>9952164 - Disclosure - Accumulated Other Comprehensive Income (Loss)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxes" roleURI="http://www.protolabs.com/role/IncomeTaxes">
        <link:definition>9952165 - Disclosure - Income Taxes</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentReporting" roleURI="http://www.protolabs.com/role/SegmentReporting">
        <link:definition>9952166 - Disclosure - Segment Reporting</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SubsequentEvent" roleURI="http://www.protolabs.com/role/SubsequentEvent">
        <link:definition>9952167 - Disclosure - Subsequent Event</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomeperCommonShareTables" roleURI="http://www.protolabs.com/role/NetIncomeperCommonShareTables">
        <link:definition>9954471 - Disclosure - Net Income per Common Share (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssetsTables" roleURI="http://www.protolabs.com/role/GoodwillandOtherIntangibleAssetsTables">
        <link:definition>9954472 - Disclosure - Goodwill and Other Intangible Assets (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsTables" roleURI="http://www.protolabs.com/role/FairValueMeasurementsTables">
        <link:definition>9954473 - Disclosure - Fair Value Measurements (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesTables" roleURI="http://www.protolabs.com/role/MarketableSecuritiesTables">
        <link:definition>9954474 - Disclosure - Marketable Securities (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoryTables" roleURI="http://www.protolabs.com/role/InventoryTables">
        <link:definition>9954475 - Disclosure - Inventory (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockBasedCompensationTables" roleURI="http://www.protolabs.com/role/StockBasedCompensationTables">
        <link:definition>9954476 - Disclosure - Stock-Based Compensation (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveIncomeLossTables" roleURI="http://www.protolabs.com/role/AccumulatedOtherComprehensiveIncomeLossTables">
        <link:definition>9954477 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentReportingTables" roleURI="http://www.protolabs.com/role/SegmentReportingTables">
        <link:definition>9954478 - Disclosure - Segment Reporting (Tables)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomeperCommonShareNarrativeDetails" roleURI="http://www.protolabs.com/role/NetIncomeperCommonShareNarrativeDetails">
        <link:definition>9954479 - Disclosure - Net Income per Common Share - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="NetIncomeperCommonShareScheduleofComputationOfBasicandDilutedNetIncomePerShareDetails" roleURI="http://www.protolabs.com/role/NetIncomeperCommonShareScheduleofComputationOfBasicandDilutedNetIncomePerShareDetails">
        <link:definition>9954480 - Disclosure - Net Income per Common Share -Schedule of Computation Of Basic and Diluted Net Income Per Share (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssetsScheduleofIntangibleAssetsOtherThanGoodwillDetails" roleURI="http://www.protolabs.com/role/GoodwillandOtherIntangibleAssetsScheduleofIntangibleAssetsOtherThanGoodwillDetails">
        <link:definition>9954481 - Disclosure - Goodwill and Other Intangible Assets - Schedule of Intangible Assets Other Than Goodwill (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssetsNarrativeDetails" roleURI="http://www.protolabs.com/role/GoodwillandOtherIntangibleAssetsNarrativeDetails">
        <link:definition>9954482 - Disclosure - Goodwill and Other Intangible Assets - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="GoodwillandOtherIntangibleAssetsFutureAmortizationExpenseDetails" roleURI="http://www.protolabs.com/role/GoodwillandOtherIntangibleAssetsFutureAmortizationExpenseDetails">
        <link:definition>9954483 - Disclosure - Goodwill and Other Intangible Assets - Future Amortization Expense (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="FairValueMeasurementsFinancialAssetsMeasuredAtFairValueOnARecurringBasisDetails" roleURI="http://www.protolabs.com/role/FairValueMeasurementsFinancialAssetsMeasuredAtFairValueOnARecurringBasisDetails">
        <link:definition>9954484 - Disclosure - Fair Value Measurements - Financial Assets Measured At Fair Value On A Recurring Basis (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesShortTermandLongTermMarketableSecuritiesDetails" roleURI="http://www.protolabs.com/role/MarketableSecuritiesShortTermandLongTermMarketableSecuritiesDetails">
        <link:definition>9954485 - Disclosure - Marketable Securities - Short-Term and Long-Term Marketable Securities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="MarketableSecuritiesMaturitiesofAvailableForSaleDebtSecuritiesDetails" roleURI="http://www.protolabs.com/role/MarketableSecuritiesMaturitiesofAvailableForSaleDebtSecuritiesDetails">
        <link:definition>9954486 - Disclosure - Marketable Securities - Maturities of Available-For-Sale Debt Securities (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="InventoryDetails" roleURI="http://www.protolabs.com/role/InventoryDetails">
        <link:definition>9954487 - Disclosure - Inventory (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockBasedCompensationNarrativeDetails" roleURI="http://www.protolabs.com/role/StockBasedCompensationNarrativeDetails">
        <link:definition>9954488 - Disclosure - Stock-Based Compensation - Narrative (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockBasedCompensationOptionActivityDetails" roleURI="http://www.protolabs.com/role/StockBasedCompensationOptionActivityDetails">
        <link:definition>9954489 - Disclosure - Stock-Based Compensation - Option Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockBasedCompensationWeightedAverageAssumptionsDetails" roleURI="http://www.protolabs.com/role/StockBasedCompensationWeightedAverageAssumptionsDetails">
        <link:definition>9954490 - Disclosure - Stock-Based Compensation - Weighted Average Assumptions (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="StockBasedCompensationStockActivityDetails" roleURI="http://www.protolabs.com/role/StockBasedCompensationStockActivityDetails">
        <link:definition>9954491 - Disclosure - Stock-Based Compensation - Stock Activity (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="AccumulatedOtherComprehensiveIncomeLossChangesInAccumulatedOtherComprehensiveIncomeLossDetails" roleURI="http://www.protolabs.com/role/AccumulatedOtherComprehensiveIncomeLossChangesInAccumulatedOtherComprehensiveIncomeLossDetails">
        <link:definition>9954492 - Disclosure - Accumulated Other Comprehensive Income (Loss) - Changes In Accumulated Other Comprehensive Income (Loss) (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="IncomeTaxesDetails" roleURI="http://www.protolabs.com/role/IncomeTaxesDetails">
        <link:definition>9954493 - Disclosure - Income Taxes (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentReportingRevenuebyGeographicAreasDetails" roleURI="http://www.protolabs.com/role/SegmentReportingRevenuebyGeographicAreasDetails">
        <link:definition>9954494 - Disclosure - Segment Reporting - Revenue by Geographic Areas (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentReportingIncomeFromOperationbyGeographicAreasDetails" roleURI="http://www.protolabs.com/role/SegmentReportingIncomeFromOperationbyGeographicAreasDetails">
        <link:definition>9954495 - Disclosure - Segment Reporting - Income From Operation by Geographic Areas (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentReportingLongLivedAssetsbyGeographicAreasDetails" roleURI="http://www.protolabs.com/role/SegmentReportingLongLivedAssetsbyGeographicAreasDetails">
        <link:definition>9954496 - Disclosure - Segment Reporting - Long-Lived Assets by Geographic Areas (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SegmentReportingDisaggregationofRevenueDetails" roleURI="http://www.protolabs.com/role/SegmentReportingDisaggregationofRevenueDetails">
        <link:definition>9954497 - Disclosure - Segment Reporting - Disaggregation of Revenue (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType id="SubsequentEventDetails" roleURI="http://www.protolabs.com/role/SubsequentEventDetails">
        <link:definition>9954498 - Disclosure - Subsequent Event (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xs:appinfo>
  </xs:annotation>
  <xs:element id="prlb_ClosureOfJapanBusiness" abstract="false" name="ClosureOfJapanBusiness" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="prlb_ScheduleOfSharebasedPaymentAwardAwardsOtherThanStockOptionsValuationAssumptionsTableTextBlock" abstract="false" name="ScheduleOfSharebasedPaymentAwardAwardsOtherThanStockOptionsValuationAssumptionsTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="prlb_IncomeFromOperationsByGeographicAreaTableTextBlock" abstract="false" name="IncomeFromOperationsByGeographicAreaTableTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:textBlockItemType"/>
  <xs:element id="prlb_EarningsPerShareBasicAndDilutedEPSAbstract" abstract="true" name="EarningsPerShareBasicAndDilutedEPSAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="prlb_SoftwarePlatformMember" abstract="true" name="SoftwarePlatformMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_A3DHubsInc.HubsMember" abstract="true" name="A3DHubsInc.HubsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" abstract="false" name="FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="prlb_LongTermIncentivePlan2022Member" abstract="true" name="LongTermIncentivePlan2022Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="prlb_ESPPMember" abstract="true" name="ESPPMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_EmployeeStockPurchasePlanOfferingPeriod" abstract="false" name="EmployeeStockPurchasePlanOfferingPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="prlb_PercentageOfTargetNumberCapableOfBeingEarnedAndVestingLowerLimit" abstract="false" name="PercentageOfTargetNumberCapableOfBeingEarnedAndVestingLowerLimit" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="prlb_PercentageOfTargetNumberCapableOfBeingEarnedAndVestingUpperLimit" abstract="false" name="PercentageOfTargetNumberCapableOfBeingEarnedAndVestingUpperLimit" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="prlb_EmployeeStockPurchasePlanMember" abstract="true" name="EmployeeStockPurchasePlanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceChange" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceChange" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="prlb_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceChangeWeightedAverageGrantDateFairValue" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPerformanceChangeWeightedAverageGrantDateFairValue" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:perShareItemType"/>
  <xs:element id="prlb_EffectiveIncomeTaxRateContinuingOperationsIncreaseDecreaseDuringThePeriod" abstract="false" name="EffectiveIncomeTaxRateContinuingOperationsIncreaseDecreaseDuringThePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:percentItemType"/>
  <xs:element id="prlb_UnitedStatesSegmentMember" abstract="true" name="UnitedStatesSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_EuropeSegmentMember" abstract="true" name="EuropeSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_CorporateUnallocatedAndJapanSegmentMember" abstract="true" name="CorporateUnallocatedAndJapanSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_InjectionMoldingProtomoldMember" abstract="true" name="InjectionMoldingProtomoldMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_CNCMachiningFirstcutMember" abstract="true" name="CNCMachiningFirstcutMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_ThreeDPrintingFinelineMember" abstract="true" name="ThreeDPrintingFinelineMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_SheetMetalMember" abstract="true" name="SheetMetalMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
  <xs:element id="prlb_OtherProductsMember" abstract="true" name="OtherProductsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types1:domainItemType"/>
</xs:schema>
