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<edgarSubmission xsi:schemaLocation="http://www.sec.gov/edgar/thirteenffiler eis_13F_Filer.xsd" xmlns="http://www.sec.gov/edgar/thirteenffiler" xmlns:ns1="http://www.sec.gov/edgar/common" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <schemaVersion>X0202</schemaVersion>
  <headerData>
    <submissionType>13F-HR</submissionType>
    <filerInfo>
      <liveTestFlag>LIVE</liveTestFlag>
      <filer>
        <credentials>
          <cik>0001315339</cik>
          <ccc>XXXXXXXX</ccc>
        </credentials>
      </filer>
      <periodOfReport>03-31-2026</periodOfReport>
    </filerInfo>
  </headerData>
  <formData>
    <coverPage>
      <reportCalendarOrQuarter>03-31-2026</reportCalendarOrQuarter>
      <filingManager>
        <name>FIRST FINANCIAL BANK - TRUST DIVISION</name>
        <address>
          <ns1:street1>300 HIGH STREET</ns1:street1>
          <ns1:city>HAMILTON</ns1:city>
          <ns1:stateOrCountry>OH</ns1:stateOrCountry>
          <ns1:zipCode>45011</ns1:zipCode>
        </address>
      </filingManager>
      <reportType>13F HOLDINGS REPORT</reportType>
      <form13FFileNumber>028-11427</form13FFileNumber>
      <provideInfoForInstruction5>N</provideInfoForInstruction5>
    </coverPage>
    <signatureBlock>
      <name>THERESA HOLLAND</name>
      <title>WM OPERATIONS SUPERVISOR</title>
      <phone>513-867-5560</phone>
      <signature>THERESA HOLLAND</signature>
      <city>HAMILTON</city>
      <stateOrCountry>OH</stateOrCountry>
      <signatureDate>04-01-2026</signatureDate>
    </signatureBlock>
    <summaryPage>
      <otherIncludedManagersCount>0</otherIncludedManagersCount>
      <tableEntryTotal>392</tableEntryTotal>
      <tableValueTotal>1241739998</tableValueTotal>
      <isConfidentialOmitted>false</isConfidentialOmitted>
    </summaryPage>
  </formData>
</edgarSubmission>
