<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

<documentType>4</documentType><periodOfReport>2003-05-05</periodOfReport>
<issuer><issuerCik>0000732713</issuerCik>
        <issuerName>BELLSOUTH CORP</issuerName>
<issuerTradingSymbol>BLS</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId><rptOwnerCik>0001162744</rptOwnerCik>
            <rptOwnerName>FELDSTEIN KATHLEEN F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
<reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeSecurity><securityTitle><value>Phantom Deferral Shares</value></securityTitle><conversionOrExercisePrice><value>0</value><footnoteId id="F3"/></conversionOrExercisePrice><transactionDate><value>2003-05-05</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>144.667</value></transactionShares><transactionValue><value>22.811</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2010-01-01</value><footnoteId id="F4"/></exerciseDate><expirationDate><value>2019-01-01</value><footnoteId id="F4"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>144.667</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>10927.9294</value><footnoteId id="F5"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><derivativeSecurity><securityTitle><value>Phantom Deferral Shares</value></securityTitle><conversionOrExercisePrice><value>0</value><footnoteId id="F3"/></conversionOrExercisePrice><transactionDate><value>2003-05-05</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>77.456</value></transactionShares><transactionValue><value>23.239</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2010-01-01</value><footnoteId id="F4"/></exerciseDate><expirationDate><value>2019-01-01</value><footnoteId id="F4"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>77.456</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>11005.3854</value><footnoteId id="F5"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><derivativeSecurity><securityTitle><value>Phantom Deferral Shares</value></securityTitle><conversionOrExercisePrice><value>0</value><footnoteId id="F3"/></conversionOrExercisePrice><transactionDate><value>2003-05-05</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>1928.8476</value></transactionShares><transactionValue><value>24.504</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2010-01-01</value></exerciseDate><expirationDate><value>2010-01-01</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>1928.8476</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>12934.233</value><footnoteId id="F5"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><derivativeSecurity><securityTitle><value>Phantom Deferral Shares</value></securityTitle><conversionOrExercisePrice><value>0</value><footnoteId id="F3"/></conversionOrExercisePrice><transactionDate><value>2003-05-06</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>59.4224</value></transactionShares><transactionValue><value>25.243</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2010-01-01</value></exerciseDate><expirationDate><value>2010-01-01</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>59.4224</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>12993.6554</value><footnoteId id="F2"/><footnoteId id="F5"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">SHARES OF PHANTOM STOCK ACQUIRED PURSUANT TO BELLSOUTH CORPORATION DEFERRAL PLAN IN TRANSACTION EXEMPT UNDER RULE 16b-3(d).</footnote><footnote id="F2">INCLUDES SHARES OF PHANTOM STOCK ACQUIRED AS A RESULT OF REINVESTMENT OF DIVIDENDS ACCRUED ON PHANTOM SHARES PREVIOUSLY ACQUIRED UNDER VARIOUS DEFERRAL PLANS IN TRANSACTIONS EXEMPT UNDER RULE 16b-3 AND DEFERRED INTO PHANTOM ACCOUNT.</footnote><footnote id="F3">SHARES OF PHANTOM STOCK CONVERT TO COMMON STOCK ON A ONE-FOR-ONE BASIS.</footnote><footnote id="F4">PAID OUT 1/10 PER YEAR BEGINNING ON 1/1/2010.</footnote><footnote id="F5">BALANCE OMITS 79.9219 SHARES INCORRECTLY INCLUDED FROM TOTAL HOLDINGS IN FORM 4 FILED ON FEBRUARY 26, 2003 DUE TO ARITHMATIC ERROR.</footnote></footnotes><ownerSignature><signatureName>Marcy A. Bass, Attorney in Fact</signatureName><signatureDate>2003-05-07</signatureDate></ownerSignature></ownershipDocument>

