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    <submissionType>13F-HR</submissionType>
    <filerInfo>
      <liveTestFlag>LIVE</liveTestFlag>
      <flags>
        <confirmingCopyFlag>false</confirmingCopyFlag>
        <returnCopyFlag>true</returnCopyFlag>
        <overrideInternetFlag>false</overrideInternetFlag>
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      <filer>
        <credentials>
          <cik>0000351173</cik>
          <ccc>XXXXXXXX</ccc>
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      <periodOfReport>03-31-2016</periodOfReport>
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      <reportCalendarOrQuarter>03-31-2016</reportCalendarOrQuarter>
      <filingManager>
        <name>FRONTIER CAPITAL MANAGEMENT CO LLC</name>
        <address>
          <ns1:street1>99 SUMMER ST</ns1:street1>
          <ns1:city>BOSTON</ns1:city>
          <ns1:stateOrCountry>MA</ns1:stateOrCountry>
          <ns1:zipCode>02110</ns1:zipCode>
        </address>
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      <reportType>13F HOLDINGS REPORT</reportType>
      <form13FFileNumber>028-01185</form13FFileNumber>
      <provideInfoForInstruction5>N</provideInfoForInstruction5>
    </coverPage>
    <signatureBlock>
      <name>Mr. William J. Ballou</name>
      <title>Chief Operating Officer &amp; General Counsel</title>
      <phone>(617) 261-0777</phone>
      <signature>/S/ William J. Ballou</signature>
      <city>Boston</city>
      <stateOrCountry>MA</stateOrCountry>
      <signatureDate>05-04-2016</signatureDate>
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      <tableValueTotal>12563849065</tableValueTotal>
      <isConfidentialOmitted>false</isConfidentialOmitted>
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