<?xml version="1.0" encoding="US-ASCII"?>
<!-- DFIN New ActiveDisclosure (SM) XBRL Schema Document - http://www.dfinsolutions.com/ -->
<!-- Creation Date :2023-11-07T12:37:27.8711+00:00 -->
<!-- Copyright (c) 2023 Donnelly Financial Solutions, Inc. All Rights Reserved. -->
<xsd:schema targetNamespace="http://www.bioatla.com/20230930" attributeFormDefault="unqualified" elementFormDefault="qualified" xmlns:dtr-types="http://www.xbrl.org/dtr/type/2022-03-31" xmlns:enum2="http://xbrl.org/2020/extensible-enumerations-2.0" xmlns:srt="http://fasb.org/srt/2023" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:us-gaap="http://fasb.org/us-gaap/2023" xmlns:dei="http://xbrl.sec.gov/dei/2023" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xmlns:bcab="http://www.bioatla.com/20230930" xmlns:xlink="http://www.w3.org/1999/xlink">
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-instance-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/instance"/>
  <xsd:import schemaLocation="http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" namespace="http://www.xbrl.org/2003/linkbase"/>
  <xsd:import schemaLocation="http://www.xbrl.org/2005/xbrldt-2005.xsd" namespace="http://xbrl.org/2005/xbrldt"/>
  <xsd:import schemaLocation="https://xbrl.sec.gov/dei/2023/dei-2023.xsd" namespace="http://xbrl.sec.gov/dei/2023"/>
  <xsd:import schemaLocation="https://www.xbrl.org/dtr/type/2022-03-31/types.xsd" namespace="http://www.xbrl.org/dtr/type/2022-03-31"/>
  <xsd:import schemaLocation="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd" namespace="http://fasb.org/us-gaap/2023"/>
  <xsd:import schemaLocation="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd" namespace="http://fasb.org/srt/2023"/>
  <xsd:annotation>
    <xsd:appinfo>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bcab-20230930_lab.xml" xlink:role="http://www.xbrl.org/2003/role/labelLinkbaseRef" xlink:title="Labels link" xlink:type="simple"/>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bcab-20230930_pre.xml" xlink:role="http://www.xbrl.org/2003/role/presentationLinkbaseRef" xlink:title="Presentation link" xlink:type="simple"/>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bcab-20230930_def.xml" xlink:role="http://www.xbrl.org/2003/role/definitionLinkbaseRef" xlink:title="Definition link" xlink:type="simple"/>
      <link:linkbaseRef xlink:arcrole="http://www.w3.org/1999/xlink/properties/linkbase" xlink:href="bcab-20230930_cal.xml" xlink:role="http://www.xbrl.org/2003/role/calculationLinkbaseRef" xlink:title="Calculation link" xlink:type="simple"/>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DocumentDocumentAndEntityInformation" id="Role_DocumentDocumentAndEntityInformation">
        <link:definition>100000 - Document - Document And Entity Information</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/StatementCondensedConsolidatedBalanceSheets1" id="StatementCondensedConsolidatedBalanceSheets1">
        <link:definition>100010 - Statement - Condensed 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureLeasesMaturitiesOfOperatingLeaseLiabilitiesDetails2" id="DisclosureLeasesMaturitiesOfOperatingLeaseLiabilitiesDetails2">
        <link:definition>100020 - Disclosure - Leases - Maturities of Operating Lease Liabilities (Details) 2</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/StatementCondensedConsolidatedBalanceSheetsParenthetical" id="StatementCondensedConsolidatedBalanceSheetsParenthetical">
        <link:definition>100030 - Statement - Condensed 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/StatementUnauditedCondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss1" id="StatementUnauditedCondensedConsolidatedStatementsOfOperationsAndComprehensiveLoss1">
        <link:definition>100040 - Statement - Unaudited Condensed Consolidated Statements of Operations and Comprehensive 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/StatementUnauditedCondensedConsolidatedStatementOfStockholdersEquity" id="StatementUnauditedCondensedConsolidatedStatementOfStockholdersEquity">
        <link:definition>100050 - Statement - Unaudited Condensed Consolidated Statement of Stockholders' 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/StatementUnauditedCondensedConsolidatedStatementsOfCashFlows" id="StatementUnauditedCondensedConsolidatedStatementsOfCashFlows">
        <link:definition>100060 - Statement - Unaudited Condensed 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureOrganizationAndSummaryOfSignificantAccountingPolicies" id="Role_DisclosureOrganizationAndSummaryOfSignificantAccountingPolicies">
        <link:definition>100070 - Disclosure - Organization and Summary of Significant Accounting Policies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureBalanceSheetDetails" id="Role_DisclosureBalanceSheetDetails">
        <link:definition>100080 - Disclosure - Balance Sheet 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureFairValueMeasurements" id="Role_DisclosureFairValueMeasurements">
        <link:definition>100090 - 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureDebt" id="DisclosureDebt">
        <link:definition>100100 - Disclosure - Debt</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureLeases" id="DisclosureLeases">
        <link:definition>100110 - Disclosure - Leases</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureCommitmentsAndContingencies" id="Role_DisclosureCommitmentsAndContingencies">
        <link:definition>100120 - Disclosure - Commitments and Contingencies</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureStockholdersEquity" id="DisclosureStockholdersEquity">
        <link:definition>100130 - Disclosure - Stockholders' 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureProfitsInterestIncentivePlan" id="Role_DisclosureProfitsInterestIncentivePlan">
        <link:definition>100140 - Disclosure - Profits Interest Incentive Plan</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureCollaborationLicenseAndOptionAgreements" id="Role_DisclosureCollaborationLicenseAndOptionAgreements">
        <link:definition>100150 - Disclosure - Collaboration, License and Option Agreements</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureRelatedPartyTransactions1" id="DisclosureRelatedPartyTransactions1">
        <link:definition>100160 - Disclosure - Related Party Transactions</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_Disclosure401KPlan" id="Role_Disclosure401KPlan">
        <link:definition>100170 - Disclosure - 401(k) Plan</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureEXUMABiotechCorp" id="Role_DisclosureEXUMABiotechCorp">
        <link:definition>100180 - Disclosure - EXUMA Biotech Corp.</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureSubsequentEvents" id="Role_DisclosureSubsequentEvents">
        <link:definition>100190 - Disclosure - Subsequent Events</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesPolicies" id="Role_DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesPolicies">
        <link:definition>100200 - Disclosure - Organization and Summary of Significant Accounting Policies (Policies)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
      <link:roleType roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesTables" id="Role_DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesTables">
        <link:definition>100210 - Disclosure - Organization and Summary of Significant Accounting Policies (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureBalanceSheetDetailsTables" id="Role_DisclosureBalanceSheetDetailsTables">
        <link:definition>100220 - Disclosure - Balance Sheet Details (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureLeasesTables" id="DisclosureLeasesTables">
        <link:definition>100230 - Disclosure - Leases (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureCommitmentsAndContingenciesTables" id="Role_DisclosureCommitmentsAndContingenciesTables">
        <link:definition>100240 - Disclosure - Commitments and Contingencies (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureStockholdersEquityTables" id="DisclosureStockholdersEquityTables">
        <link:definition>100250 - Disclosure - Stockholders' Equity (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureProfitsInterestIncentivePlanTables" id="Role_DisclosureProfitsInterestIncentivePlanTables">
        <link:definition>100260 - Disclosure - Profits Interest Incentive Plan (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails" id="Role_DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesAdditionalInformationDetails">
        <link:definition>100270 - Disclosure - Organization and Summary of Significant Accounting Policies - Additional Information (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesScheduleOfAntidilutiveSecuritiesExcludedFromCalculationOfDilutedNetLossPerS" id="DisclosureOrganizationAndSummaryOfSignificantAccountingPoliciesScheduleOfAntidilutiveSecuritiesExcludedFromCalculationOfDilutedNetLossPerS">
        <link:definition>100280 - Disclosure - Organization and Summary of Significant Accounting Policies - Schedule of Anti-dilutive Securities Excluded from Calculation of Diluted Net Loss 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureBalanceSheetDetailsScheduleOfPrepaidExpensesOtherCurrentAssetsDetails" id="Role_DisclosureBalanceSheetDetailsScheduleOfPrepaidExpensesOtherCurrentAssetsDetails">
        <link:definition>100290 - Disclosure - Balance Sheet Details - Schedule Of Prepaid Expenses Other Current Assets (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureBalanceSheetDetailsScheduleOfPropertyAndEquipmentDetails" id="Role_DisclosureBalanceSheetDetailsScheduleOfPropertyAndEquipmentDetails">
        <link:definition>100300 - Disclosure - Balance Sheet Details - Schedule of Property and Equipment (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureBalanceSheetDetailsScheduleOfAccountsPayableAndAccruedExpensesDetails" id="Role_DisclosureBalanceSheetDetailsScheduleOfAccountsPayableAndAccruedExpensesDetails">
        <link:definition>100310 - Disclosure - Balance Sheet Details - Schedule of Accounts Payable and Accrued Expenses (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureFairValueMeasurementsAdditionalInformationDetails" id="DisclosureFairValueMeasurementsAdditionalInformationDetails">
        <link:definition>100320 - Disclosure - Fair Value Measurements - Additional Information (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureDebtAdditionalInformationDetails" id="DisclosureDebtAdditionalInformationDetails">
        <link:definition>100330 - Disclosure - Debt - Additional Information (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureLeasesAdditionalInformationDetails" id="DisclosureLeasesAdditionalInformationDetails">
        <link:definition>100340 - Disclosure - Leases (Additional Information) (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureLeasesComponentsOfLeaseExpenseDetails" id="DisclosureLeasesComponentsOfLeaseExpenseDetails">
        <link:definition>100350 - Disclosure - Leases - Components of Lease 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureLeasesSummaryOfWeightedAverageRemainingLeaseTermAndWeightedAverageDiscountRateDetails" id="DisclosureLeasesSummaryOfWeightedAverageRemainingLeaseTermAndWeightedAverageDiscountRateDetails">
        <link:definition>100360 - Disclosure - Leases - Summary of Weighted Average Remaining Lease Term And Weighted Average Discount Rate (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureLeasesSupplementalCashFlowInformationRelatedToLeasesDetails" id="DisclosureLeasesSupplementalCashFlowInformationRelatedToLeasesDetails">
        <link:definition>100370 - Disclosure - Leases - Supplemental Cash Flow Information Related to Leases (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureLeasesMaturitiesOfOperatingLeaseLiabilitiesDetails" id="DisclosureLeasesMaturitiesOfOperatingLeaseLiabilitiesDetails">
        <link:definition>100380 - Disclosure - Leases - Maturities of Operating Lease Liabilities (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureCommitmentsAndContingenciesScheduleOfExpectedFutureMinimumPaymentsUnderTheNonCancelableOperatingLeaseDetails" id="DisclosureCommitmentsAndContingenciesScheduleOfExpectedFutureMinimumPaymentsUnderTheNonCancelableOperatingLeaseDetails">
        <link:definition>100390 - Disclosure - Commitments and Contingencies - Schedule of Expected Future Minimum Payments Under the Non Cancelable Operating Lease (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureStockholdersEquityAdditionalInformationDetails" id="DisclosureStockholdersEquityAdditionalInformationDetails">
        <link:definition>100400 - Disclosure - Stockholders' Equity - Additional Information (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureStockholdersEquityScheduleOfStockbasedCompensationExpenseDetails" id="DisclosureStockholdersEquityScheduleOfStockbasedCompensationExpenseDetails">
        <link:definition>100410 - Disclosure - Stockholders' Equity - Schedule of Stock-based Compensation 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureStockholdersEquitySummaryOfRestrictedStockUnitsDetails" id="DisclosureStockholdersEquitySummaryOfRestrictedStockUnitsDetails">
        <link:definition>100420 - Disclosure - Stockholders' Equity - Summary of Restricted Stock Units (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureStockholdersEquitySummaryOfStockOptionActivityDetails" id="DisclosureStockholdersEquitySummaryOfStockOptionActivityDetails">
        <link:definition>100430 - Disclosure - Stockholders' Equity - Summary of Stock 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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureStockholdersEquitySummaryOfAssumptionsUsedInBlackscholesModelDetails" id="DisclosureStockholdersEquitySummaryOfAssumptionsUsedInBlackscholesModelDetails">
        <link:definition>100440 - Disclosure - Stockholders' Equity - Summary of Assumptions Used in Black-Scholes Model (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureStockholdersEquityScheduleOfCommonStockReservedForFutureIssuanceDetails" id="DisclosureStockholdersEquityScheduleOfCommonStockReservedForFutureIssuanceDetails">
        <link:definition>100450 - Disclosure - Stockholders' Equity - Schedule of Common Stock Reserved for Future Issuance (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureProfitsInterestIncentivePlanAllocationOfEquityBasedCompensationForAllClassBUnitsDetails" id="Role_DisclosureProfitsInterestIncentivePlanAllocationOfEquityBasedCompensationForAllClassBUnitsDetails">
        <link:definition>100460 - Disclosure - Profits Interest Incentive Plan - Allocation of equity-based Compensation for all class B units (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureProfitsInterestIncentivePlanAdditionalInformationDetails" id="DisclosureProfitsInterestIncentivePlanAdditionalInformationDetails">
        <link:definition>100470 - Disclosure - Profits Interest Incentive Plan (Additional Information) (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureCollaborationLicenseAndOptionAgreementsAdditionalInformationDetails" id="Role_DisclosureCollaborationLicenseAndOptionAgreementsAdditionalInformationDetails">
        <link:definition>100480 - Disclosure - Collaboration, License and Option Agreements - Additional Information (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails" id="Role_DisclosureRelatedPartyTransactionsAdditionalInformationDetails">
        <link:definition>100490 - Disclosure - Related Party Transactions - Additional Information (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/Disclosure401kPlanAdditionalInformationDetails" id="Disclosure401kPlanAdditionalInformationDetails">
        <link:definition>100500 - Disclosure - 401(k) Plan - Additional Information (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 roleURI="http://www.bioatla.com/20230930/taxonomy/role/DisclosureExumaBiotechCorpAdditionalInformationDetails" id="DisclosureExumaBiotechCorpAdditionalInformationDetails">
        <link:definition>100510 - Disclosure - EXUMA Biotech corp. - Additional Information (Details)</link:definition>
        <link:usedOn>link:presentationLink</link:usedOn>
        <link:usedOn>link:calculationLink</link:usedOn>
        <link:usedOn>link:definitionLink</link:usedOn>
      </link:roleType>
    </xsd:appinfo>
  </xsd:annotation>
  <xsd:element id="bcab_LaboratoryEquipmentMember" name="LaboratoryEquipmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_TaxRelatedToNetSettlementOfEquityAwardsIncludedInAccountsPayableAndAccruedExpenses" name="TaxRelatedToNetSettlementOfEquityAwardsIncludedInAccountsPayableAndAccruedExpenses" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_WarrantsForThePurchaseOfCommonStock" name="WarrantsForThePurchaseOfCommonStock" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_RsusFullyVestedOnTheModificationDateNumberOfShares" name="RsusFullyVestedOnTheModificationDateNumberOfShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_AmendedBeiGeneCollaborationMember" name="AmendedBeiGeneCollaborationMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_RsusUnvestedOnModificationDateNumberOfShares" name="RsusUnvestedOnModificationDateNumberOfShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_CompensationExpenseOnIssuanceOfDirectorCompensation" name="CompensationExpenseOnIssuanceOfDirectorCompensation" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_CommonSharesAuthorizedForIssuance" name="CommonSharesAuthorizedForIssuance" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false"/>
  <xsd:element id="bcab_DescriptionOfAgreementWithRelatedParty" name="DescriptionOfAgreementWithRelatedParty" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_AccruedResearchAndDevelopmentExpenseCurrent" name="AccruedResearchAndDevelopmentExpenseCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_DebtInstrumentOutstandingPrincipalAmount" name="DebtInstrumentOutstandingPrincipalAmount" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bcab_LessorOperatingLeasesOptionToExtend" name="LessorOperatingLeasesOptionToExtend" type="xbrli:durationItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_ExclusiveLicenseAgreementWithEXUMABiotechCorpTextBlock" name="ExclusiveLicenseAgreementWithEXUMABiotechCorpTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_TaxesrelatedtonetsharesettlementofequityawardsShares" name="TaxesrelatedtonetsharesettlementofequityawardsShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_WarrantsMember" name="WarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_ModificationOfTwoThousandTwentyEquityIncentivePlanAndCertainAwardsMember" name="ModificationOfTwoThousandTwentyEquityIncentivePlanAndCertainAwardsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_ExclusiveLicenseAgreementAbstract" name="ExclusiveLicenseAgreementAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_HimalayaTherapeuticsSEZCMember" name="HimalayaTherapeuticsSEZCMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_OtherPrepaidExpensesAndCurrentAssets" name="OtherPrepaidExpensesAndCurrentAssets" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bcab_CollaborationLicenseAndOptionAgreementsAbstract" name="CollaborationLicenseAndOptionAgreementsAbstract" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_RecalculatedCompensationCostOfTheModifiedOptions" name="RecalculatedCompensationCostOfTheModifiedOptions" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_ScheduleOfPrepaidExpensesOtherCurrentAssetsTableTextBlock" name="ScheduleOfPrepaidExpensesOtherCurrentAssetsTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_CommonStockWarrantsMember" name="CommonStockWarrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_StockIssuedDuringPeriodSharesConversionOfClassBCommonStock" name="StockIssuedDuringPeriodSharesConversionOfClassBCommonStock" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_EmployeesStockPurchasePlanMember" name="EmployeesStockPurchasePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_NumberOfOptionsUnvestedOnModificationDateNumberOfShares" name="NumberOfOptionsUnvestedOnModificationDateNumberOfShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_CarolynAndersonShortMember" name="CarolynAndersonShortMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_LiabilityToLicensor" name="LiabilityToLicensor" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_CompanyFormationDate" name="CompanyFormationDate" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_OtherIncomeExpense" name="OtherIncomeExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_CollaborationAgreementStartDate" name="CollaborationAgreementStartDate" type="xbrli:gYearMonthItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_PrivatePlacementOfCommonStockMember" name="PrivatePlacementOfCommonStockMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_LiquidityAndGoingConcernPolicyTextBlock" name="LiquidityAndGoingConcernPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_PPPLoanMember" name="PPPLoanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_TaxesRelatedToNetShareSettlementOfEquityAwards" name="TaxesRelatedToNetShareSettlementOfEquityAwards" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bcab_TwoThousandTwentyPlanMember" name="TwoThousandTwentyPlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_CommonSockWrantsMember" name="CommonSockWrantsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_FurnitureFixturesAndOfficeEquipmentMember" name="FurnitureFixturesAndOfficeEquipmentMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_OrganizationPolicyTextBlock" name="OrganizationPolicyTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_NumberOfRsusUnvestedOnModificationDateNumberOfShares" name="NumberOfRsusUnvestedOnModificationDateNumberOfShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_ReimbursementOfManufacturingCosts" name="ReimbursementOfManufacturingCosts" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_RecalculatedCompensationCostOnTheModifiedRsus" name="RecalculatedCompensationCostOnTheModifiedRsus" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bcab_CommonSockOtionsMember" name="CommonSockOtionsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_PrepaidResearchAndDevelopmentExpense" name="PrepaidResearchAndDevelopmentExpense" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bcab_ScheduleOfCommonStockReservedForFutureIssuanceTableTextBlock" name="ScheduleOfCommonStockReservedForFutureIssuanceTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_CashAndCashEquivalents" name="CashAndCashEquivalents" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="debit"/>
  <xsd:element id="bcab_ConstructionInProcessMember" name="ConstructionInProcessMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_AccruedEquityIssuanceCostsCurrent" name="AccruedEquityIssuanceCostsCurrent" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="instant" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_LicenseTerminationInformationDescription" name="LicenseTerminationInformationDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_EXUMAMember" name="EXUMAMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_AllocationOfEquityBasedCompensationForClassBUnitsTableTextBlock" name="AllocationOfEquityBasedCompensationForClassBUnitsTableTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_PaymentsForTaxesRelatedToNetSettlementOfEquityAwards1" name="PaymentsForTaxesRelatedToNetSettlementOfEquityAwards1" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_UpfrontNonRefundablePayment" name="UpfrontNonRefundablePayment" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_IssuanceOfCommonStockForDirectorCompensationShares" name="IssuanceOfCommonStockForDirectorCompensationShares" type="xbrli:sharesItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_TwoThousandTwentyEquityIncentivePlanMember" name="TwoThousandTwentyEquityIncentivePlanMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_CommonStockOptionsAndRestrictedStockUnitsMember" name="CommonStockOptionsAndRestrictedStockUnitsMember" type="dtr-types:domainItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="true"/>
  <xsd:element id="bcab_CollaborationLicenseAndOptionAgreementsTextBlock" name="CollaborationLicenseAndOptionAgreementsTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_SharesAvailableForAwardsDescription" name="SharesAvailableForAwardsDescription" type="xbrli:stringItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
  <xsd:element id="bcab_IssuanceOfCommonStockForDirectorCompensationValue" name="IssuanceOfCommonStockForDirectorCompensationValue" type="xbrli:monetaryItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false" xbrli:balance="credit"/>
  <xsd:element id="bcab_ProfitsInterestIncentivePlanTextBlock" name="ProfitsInterestIncentivePlanTextBlock" type="dtr-types:textBlockItemType" substitutionGroup="xbrli:item" xbrli:periodType="duration" nillable="true" abstract="false"/>
</xsd:schema>
