<?xml version="1.0" encoding="utf-8"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>
  <periodOfReport>2003-09-22</periodOfReport>
  <notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0001035688</issuerCik>
        <issuerName>SELECT MEDICAL CORP</issuerName>
        <issuerTradingSymbol>SEM</issuerTradingSymbol>
  </issuer>
  <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001072745</rptOwnerCik>
            <rptOwnerName>CRESSEY BRYAN C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CLARION TECHNOLOGIES INC</rptOwnerStreet1>
            <rptOwnerStreet2>235 CENTRAL AVE</rptOwnerStreet2>
            <rptOwnerCity>HOLLAND</rptOwnerCity>
            <rptOwnerState>MI</rptOwnerState>
            <rptOwnerZipCode>49423</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
      <isDirector>1</isDirector>
      <isOfficer>0</isOfficer>
      <isTenPercentOwner>0</isTenPercentOwner>
      <isOther>0</isOther>
    </reportingOwnerRelationship>
  </reportingOwner>
  <nonDerivativeTable>
    <nonDerivativeHolding>
      <securityTitle>
        <value>Common Stock</value>
      </securityTitle>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>2029008</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>I</value>
        </directOrIndirectOwnership>
        <natureOfOwnership>
          <value>See footnote</value>
          <footnoteId id="F1"/>
        </natureOfOwnership>
      </ownershipNature>
    </nonDerivativeHolding>
    <nonDerivativeHolding>
      <securityTitle>
        <value>Common Stock</value>
      </securityTitle>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>20288</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>I</value>
        </directOrIndirectOwnership>
        <natureOfOwnership>
          <value>See footnote</value>
          <footnoteId id="F2"/>
        </natureOfOwnership>
      </ownershipNature>
    </nonDerivativeHolding>
    <nonDerivativeTransaction>
      <securityTitle>
        <value>Common Stock</value>
      </securityTitle>
      <transactionDate>
        <value>2003-09-22</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>S</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>1500</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>30.0000</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>D</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>441689</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>I</value>
        </directOrIndirectOwnership>
        <natureOfOwnership>
          <value>See footnote</value>
          <footnoteId id="F3"/>
        </natureOfOwnership>
      </ownershipNature>
    </nonDerivativeTransaction>
    <nonDerivativeHolding>
      <securityTitle>
        <value>Common Stock</value>
      </securityTitle>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>120846</value>
          <footnoteId id="F4"/>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </nonDerivativeHolding>
  </nonDerivativeTable>
  <derivativeTable>
    <derivativeHolding>
      <securityTitle>
        <value>Stock Option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>29.05</value>
      </conversionOrExercisePrice>
      <exerciseDate>
        <footnoteId id="F5"/>
      </exerciseDate>
      <expirationDate>
        <value>2013-08-11</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Common Stock</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>5000</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>5000</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeHolding>
  </derivativeTable>
  <footnotes>
    <footnote id="F1">These shares are owned directly by Thoma Cressey Fund VI, L.P. ("Fund VI").  Mr. Cressey is a Principal of Thoma Cressey Equity Partners, Inc. ("TCEP"), which is the general partner of TC Partners VI, L.P., which is the general partner of Fund VI.  The Reporting Person disclaims beneficial ownership except to the extent of his proportionate ownership interests therein.</footnote>
    <footnote id="F2">These shares are owned directly by Thoma Cressey Friends Fund VI, L.P ("Friends VI").  Mr. Cressey is a Principal of TCEP, which is the general partner of TC Partners VI, L.P., which is the general partner of Friends VI.  The Reporting Person disclaims beneficial ownership except to the extent of his proportionate ownership interests therein.</footnote>
    <footnote id="F3">These shares are owned directly by Golder, Thoma, Cressey, Rauner Fund V, L.P. ("Fund V").  Mr. Cressey is a Principal of GTCR Inc. which is the general partner of GTCR V, L.P., which is the general partner of Fund V.  The Reporting Person disclaims beneficial ownership except to the extent of his proportionate ownership interests therein.</footnote>
    <footnote id="F4">These shares are owned directly by Mr. Cressey.</footnote>
    <footnote id="F5">The option vests in five equal annual installments, beginning on August 12, 2004.</footnote>
  </footnotes>
  <ownerSignature>
    <signatureName>Bryan C. Cressey</signatureName>
    <signatureDate>2003-09-23</signatureDate>
  </ownerSignature>
</ownershipDocument>

