<SUBMISSION>
<ACCESSION-NUMBER>0001181431-04-015420
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20040310
<FILING-DATE>20040312
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>LAVALLEE ROBERT H
<CIK>0001190845
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-18281
<FILM-NUMBER>04666346
</FILING-VALUES>
<BUSINESS-ADDRESS>
<STREET1>HOLOGIC INC
<STREET2>35 CROSBY DR
<CITY>BEDFORD
<STATE>MA
<ZIP>01730
<PHONE>3026312877
</BUSINESS-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>HOLOGIC INC
<CIK>0000859737
<ASSIGNED-SIC>3844
<IRS-NUMBER>042902449
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>0930
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>35 CROSBY DRIVE
<CITY>BEDFORD
<STATE>MA
<ZIP>01730
<PHONE>7819997300
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>35 CROSBY DRIVE
<CITY>BEDFORD
<STATE>MA
<ZIP>01730
</MAIL-ADDRESS>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>rrd36530.xml
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-03-10</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000859737</issuerCik>
        <issuerName>HOLOGIC INC</issuerName>
        <issuerTradingSymbol>HOLX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001190845</rptOwnerCik>
            <rptOwnerName>LAVALLEE ROBERT H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>35 CROSBY DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BEDFORD</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01730</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2004-03-10</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3063</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>20.3937</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Since September 19, 2002, the beneficial ownership of the reporting person mistakenly included an additional 243 shares of common stock that were not beneficially owned, directly or indirectly, by the reporting person. Accordingly, following the transaction(s) reported on this Form 4, the reporting person does not beneficially own, directly or indirectly, any shares of common stock of Hologic, Inc.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Robert H. Lavallee</signatureName>
        <signatureDate>2004-03-12</signatureDate>
    </ownerSignature>
</ownershipDocument>

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