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

    <documentType>4</documentType><periodOfReport>2003-12-22</periodOfReport>
    <issuer>
        <issuerCik>0000049071</issuerCik>
        <issuerName>HUMANA INC</issuerName>
        <issuerTradingSymbol>HUM</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001018656</rptOwnerCik>
            <rptOwnerName>HIPWELL ARTHUR P</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>HUMANA INC.</rptOwnerStreet1>
            <rptOwnerStreet2>500 WEST MAIN STREET</rptOwnerStreet2>
            <rptOwnerCity>LOUISVILLE</rptOwnerCity>
            <rptOwnerState>KY</rptOwnerState>
            <rptOwnerZipCode>40202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Sr VP &amp; General Counsel</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Humana Common</value><footnoteId id="F1"/></securityTitle><transactionDate><value>2003-12-22</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>G</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>851</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>D</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>98539</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Humana Common</value><footnoteId id="F1"/></securityTitle><transactionDate><value>2003-12-22</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>G</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>300</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>300</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>See Footnote</value><footnoteId id="F2"/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeHolding><securityTitle><value>Humana Common</value><footnoteId id="F1"/></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>17350</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>See Footnote</value><footnoteId id="F3"/></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><derivativeTable><derivativeHolding><securityTitle><value>Options</value><footnoteId id="F4"/></securityTitle><conversionOrExercisePrice><value>17.9375</value></conversionOrExercisePrice><exerciseDate><footnoteId id="F6"/></exerciseDate><expirationDate><value>2004-01-13</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Humana Common</value><footnoteId id="F1"/></underlyingSecurityTitle><underlyingSecurityShares><value>75000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>75000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Options</value><footnoteId id="F4"/></securityTitle><conversionOrExercisePrice><value>16.9375</value></conversionOrExercisePrice><exerciseDate><footnoteId id="F7"/></exerciseDate><expirationDate><value>2004-07-20</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Humana Common</value><footnoteId id="F1"/></underlyingSecurityTitle><underlyingSecurityShares><value>25000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>25000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Options</value><footnoteId id="F5"/></securityTitle><conversionOrExercisePrice><value>15.5938</value></conversionOrExercisePrice><exerciseDate><footnoteId id="F8"/></exerciseDate><expirationDate><footnoteId id="F8"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Humana Common</value><footnoteId id="F1"/></underlyingSecurityTitle><underlyingSecurityShares><value>127264</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>127264</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Options</value><footnoteId id="F5"/></securityTitle><conversionOrExercisePrice><value>15.5938</value></conversionOrExercisePrice><exerciseDate><footnoteId id="F9"/></exerciseDate><expirationDate><value>2008-01-15</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Humana Common</value><footnoteId id="F1"/></underlyingSecurityTitle><underlyingSecurityShares><value>4316</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>4316</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Options</value><footnoteId id="F5"/></securityTitle><conversionOrExercisePrice><value>9.5938</value></conversionOrExercisePrice><exerciseDate><footnoteId id="F10"/></exerciseDate><expirationDate><value>2009-09-09</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Humana Common</value><footnoteId id="F1"/></underlyingSecurityTitle><underlyingSecurityShares><value>50000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>50000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Options</value><footnoteId id="F5"/></securityTitle><conversionOrExercisePrice><value>12.995</value></conversionOrExercisePrice><exerciseDate><footnoteId id="F11"/></exerciseDate><expirationDate><value>2012-03-13</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Humana Common</value><footnoteId id="F1"/></underlyingSecurityTitle><underlyingSecurityShares><value>45000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>45000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Options</value><footnoteId id="F5"/></securityTitle><conversionOrExercisePrice><value>9.26</value></conversionOrExercisePrice><exerciseDate><footnoteId id="F12"/></exerciseDate><expirationDate><value>2013-03-13</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Humana Common</value><footnoteId id="F1"/></underlyingSecurityTitle><underlyingSecurityShares><value>50000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>50000</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeHolding><derivativeHolding><securityTitle><value>Phantom Stock Units</value></securityTitle><conversionOrExercisePrice><footnoteId id="F13"/></conversionOrExercisePrice><exerciseDate><footnoteId id="F13"/></exerciseDate><expirationDate><footnoteId id="F13"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Humana Common</value><footnoteId id="F1"/></underlyingSecurityTitle><underlyingSecurityShares><value>7601</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>7601</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>See Footnote</value><footnoteId id="F13"/></natureOfOwnership></ownershipNature></derivativeHolding></derivativeTable><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><footnote id="F2">Shares held on behalf of minor children.</footnote><footnote id="F3">Shares held for the benefit of reporting person as of November 30, 2003 under the Humana Retirement &amp; Savings Plan including a routine disposition of shares to fund an administrative fee assessment under a Tax-Conditioned Plan, both exempt under Rule 16b-3(c).</footnote><footnote id="F4">Right to buy pursuant to the Company's 1989 Stock Option Plan for Employees.</footnote><footnote id="F5">Right to buy pursuant to the Company's 1996 Stock Incentive Plan for Employees.</footnote><footnote id="F6">Non-Qualified stock options granted to reporting person on 1/13/94 and fully vested on 9/1/99.</footnote><footnote id="F7">Non-Qualified stock options granted to reporting person on 7/20/94 and fully vested on 9/1/99.</footnote><footnote id="F8">Non-Qualified stock options granted to reporting person on 9/17/98, fully vested on 9/1/99 with 68,800 options expiring on 1/12/05, 36,680 options expiring on 1/9/2007 and 21,784 options expiring on 1/15/2008.</footnote><footnote id="F9">Incentive stock options granted to reporting person on 9/17/98 and fully vested on 9/1/99.</footnote><footnote id="F10">Incentive and Non-Qualified stock options granted to reporting person on 9/9/99 and fully vested on 9/9/02.</footnote><footnote id="F11">Incentive and Non-Qualified stock options granted to reporting person on 3/13/02, vesting in three increments each from 3/13/03 to 3/13/05.</footnote><footnote id="F12">Incentive and Non-Qualified stock options granted to reporting person on 3/13/03, NQ options vesting in three increments from 3/13/04 to 3/13/06, and ISO's vesting on 3/13/06.</footnote><footnote id="F13">Phantom Stock Units held for the benefit of reporting person as of November 30, 2003, convertible into common stock on a 1-for-1 basis, under the Humana Excess Plan, exempt under Rule 16b-3(d).</footnote></footnotes><remarks/><ownerSignature><signatureName>Arthur P. Hipwell</signatureName><signatureDate>2003-12-22</signatureDate></ownerSignature></ownershipDocument>

