<SUBMISSION>
<ACCESSION-NUMBER>0000920148-03-000163
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20031001
<FILING-DATE>20031006
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>LABORATORY CORP OF AMERICA HOLDINGS
<CIK>0000920148
<ASSIGNED-SIC>8071
<IRS-NUMBER>133757370
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>358 S MAIN ST
<CITY>BURLINGTON
<STATE>NC
<ZIP>27215
<PHONE>3362291127
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>358 S MAIN ST
<CITY>BURLINGTON
<STATE>NC
<ZIP>27215
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>NATIONAL HEALTH LABORATORIES HOLDINGS INC
<DATE-CHANGED>19940314
</FORMER-COMPANY>
</ISSUER>
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>POWELL JAMES B
<CIK>0001044220
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-11353
<FILM-NUMBER>03930247
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>430 S SPRING STREET
<CITY>BURLINGTON
<STATE>NC
<ZIP>27215
<PHONE>3364365066
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>430 S SPRING STREET
<CITY>BURLINGTON
<STATE>NC
<ZIP>27215
</MAIL-ADDRESS>
</REPORTING-OWNER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2003-10-01</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000920148</issuerCik>
        <issuerName>LABORATORY CORP OF AMERICA HOLDINGS</issuerName>
        <issuerTradingSymbol>LH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001044220</rptOwnerCik>
            <rptOwnerName>POWELL JAMES B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>430 S SPRING STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BURLINGTON</rptOwnerCity>
            <rptOwnerState>NC</rptOwnerState>
            <rptOwnerZipCode>27215</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>

        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2003-10-01</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>57</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>28.97</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12753</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>

    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Stock award represents half the monthly Director retainer pursuant to the Laboratory Corporation of America Holdings 1995 Stock Plan for Non-Employee Directors.</footnote>
        <footnote id="F2">Amount shown reflects a 2-for-1 stock split effective on May 10, 2002.</footnote>
        <footnote id="F3">Amount includes 700 shares of indirect common stock ownership held by Allemanni LLC. Dr. Powell is the sole manager of Allemanni LLC.</footnote>
    </footnotes>


    <ownerSignature>
        <signatureName>/s/ Bradford T. Smith, Attorney-in-Fact for James B. Powell</signatureName>
        <signatureDate>2003-10-03</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
