<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>3</documentType><periodOfReport>2003-09-11</periodOfReport>
    <noSecuritiesOwned>0</noSecuritiesOwned>

    <issuer>
        <issuerCik>0000049071</issuerCik>
        <issuerName>HUMANA INC</issuerName>
        <issuerTradingSymbol>HUM</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001194004</rptOwnerCik>
            <rptOwnerName>DAMELIO FRANK A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>LUCENT TECHNOLOGIES INC.</rptOwnerStreet1>
            <rptOwnerStreet2>600 MOUNTAIN AVENUE</rptOwnerStreet2>
            <rptOwnerCity>MURRAY HILL</rptOwnerCity>
            <rptOwnerState>NJ</rptOwnerState>
            <rptOwnerZipCode>07974</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeHolding><securityTitle><value>Humana Common</value><footnoteId id="F1"/></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>0</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><footnotes><footnote id="F1">Each share of Common Stock contains a Right adopted on March 5, 1987, pursuant to the Company Rights Agreement, as amended and restated on February 14, 1996, and amended as of May 27, 1998 and March 1, 1999, which entitles holders of the Company's Common Stock, in the  event certain specified events occur, to acquire 1/100 of a share of Series A Participating Preferred Stock at a price of $145 per fractional share.</footnote></footnotes><remarks/><ownerSignature><signatureName>Frank A. D'Amelio</signatureName><signatureDate>2003-09-15</signatureDate></ownerSignature></ownershipDocument>

