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

    <documentType>4</documentType>
  <periodOfReport>2003-09-22</periodOfReport>
  <notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0001011060</issuerCik>
        <issuerName>CARDIOTECH INTERNATIONAL INC</issuerName>
        <issuerTradingSymbol>CTE</issuerTradingSymbol>
  </issuer>
  <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001253830</rptOwnerCik>
            <rptOwnerName>BARRETTI MICHAEL L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>78 E OLYMPIA AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WOBURN</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01801</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
      <isDirector>1</isDirector>
      <isOfficer>0</isOfficer>
      <isTenPercentOwner>0</isTenPercentOwner>
      <isOther>0</isOther>
    </reportingOwnerRelationship>
  </reportingOwner>
  <derivativeTable>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>1.125</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>1998-09-03</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>12819</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>1.125</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>1998-09-03</value>
      </exerciseDate>
      <expirationDate>
        <value>2008-09-02</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>12819</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>12819</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>.75</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>1999-08-12</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>14444</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>.75</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>1999-08-12</value>
      </exerciseDate>
      <expirationDate>
        <value>2009-08-11</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>14444</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>27263</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>.50</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>2000-01-03</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>30000</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>.50</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>2000-01-03</value>
      </exerciseDate>
      <expirationDate>
        <value>2010-01-01</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
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        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>57263</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>.50</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>2000-01-03</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>79000</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>.50</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>2000-01-03</value>
      </exerciseDate>
      <expirationDate>
        <value>2010-01-02</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>79000</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>136263</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>2.0625</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>2000-10-26</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>19625</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>2.0625</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>2000-10-26</value>
      </exerciseDate>
      <expirationDate>
        <value>2010-10-25</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>19625</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>155888</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>1.10</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>2001-04-30</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>25000</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>1.10</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>2001-04-30</value>
      </exerciseDate>
      <expirationDate>
        <value>2011-04-29</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>25000</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>180888</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>1.61</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>2001-10-01</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>25522</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>1.61</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>2001-10-01</value>
      </exerciseDate>
      <expirationDate>
        <value>2011-09-30</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>25522</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>206410</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>1.25</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>1998-12-01</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>40000</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>1.25</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>1998-12-01</value>
      </exerciseDate>
      <expirationDate>
        <value>2003-11-30</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>40000</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>246410</value>
        </sharesOwnedFollowingTransaction>
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      <ownershipNature>
        <directOrIndirectOwnership>
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    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
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      </conversionOrExercisePrice>
      <transactionDate>
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      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
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      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
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        </transactionShares>
        <transactionPricePerShare>
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        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>1998-12-01</value>
      </exerciseDate>
      <expirationDate>
        <value>2003-11-30</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
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        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
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        </sharesOwnedFollowingTransaction>
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      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
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    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>1.59</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>2002-10-28</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>A</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
      </transactionCoding>
      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>27373</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>1.59</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>A</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>2002-10-28</value>
      </exerciseDate>
      <expirationDate>
        <value>2012-10-27</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
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        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>313783</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
    <derivativeTransaction>
      <securityTitle>
        <value>Stock option</value>
      </securityTitle>
      <conversionOrExercisePrice>
        <value>.50</value>
      </conversionOrExercisePrice>
      <transactionDate>
        <value>2003-09-22</value>
      </transactionDate>
      <transactionCoding>
        <transactionFormType>4</transactionFormType>
        <transactionCode>S</transactionCode>
        <equitySwapInvolved>0</equitySwapInvolved>
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      <transactionTimeliness>
        <value></value>
      </transactionTimeliness>
      <transactionAmounts>
        <transactionShares>
          <value>5000</value>
        </transactionShares>
        <transactionPricePerShare>
          <value>.50</value>
        </transactionPricePerShare>
        <transactionAcquiredDisposedCode>
          <value>D</value>
        </transactionAcquiredDisposedCode>
      </transactionAmounts>
      <exerciseDate>
        <value>2001-01-03</value>
      </exerciseDate>
      <expirationDate>
        <value>2010-01-02</value>
      </expirationDate>
      <underlyingSecurity>
        <underlyingSecurityTitle>
          <value>Stock option</value>
        </underlyingSecurityTitle>
        <underlyingSecurityShares>
          <value>5000</value>
        </underlyingSecurityShares>
      </underlyingSecurity>
      <postTransactionAmounts>
        <sharesOwnedFollowingTransaction>
          <value>308783</value>
        </sharesOwnedFollowingTransaction>
      </postTransactionAmounts>
      <ownershipNature>
        <directOrIndirectOwnership>
          <value>D</value>
        </directOrIndirectOwnership>
      </ownershipNature>
    </derivativeTransaction>
  </derivativeTable>
  <ownerSignature>
    <signatureName>/s/Michael L. Barretti</signatureName>
    <signatureDate>2003-09-23</signatureDate>
  </ownerSignature>
</ownershipDocument>

