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

    <documentType>4</documentType><periodOfReport>2003-07-01</periodOfReport>
    <issuer>
        <issuerCik>0000740260</issuerCik>
        <issuerName>VENTAS INC</issuerName>
        <issuerTradingSymbol>VTR</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001198222</rptOwnerCik>
            <rptOwnerName>ROSENBERG SHELI  Z</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><nonDerivativeSecurity><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-07-01</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>494</value></transactionShares><transactionValue><value>15.18</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>26908.889</value><footnoteId id="F1"/><footnoteId id="F2"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeSecurity><footnotes><footnote id="F1">As of July 1, 2003 Reporting Person also owns options to purchase 20,000 shares of the Issuer's common stock.</footnote><footnote id="F2">Includes 478.159 shares acquired on June 24, 2003 under the Ventas, Inc. Distribution Reinvestment and Stock Purchase Plan.</footnote></footnotes><ownerSignature><signatureName>Sheli Z. Rosenberg, By: T. Richard Riney Attorney-in-Fact</signatureName><signatureDate>2003-07-02</signatureDate></ownerSignature></ownershipDocument>
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X0101
4
2003-07-01
0000740260
VENTAS INC
VTR
0001198222
ROSENBERG SHELI  Z
1
0
0
0
Common Stock
2003-07-01
4
A
0
494
15.18
A
26908.889
D
As of July 1, 2003 Reporting Person also owns options to purchase 20,000 shares of the Issuer's common stock.
Includes 478.159 shares acquired on June 24, 2003 under the Ventas, Inc. Distribution Reinvestment and Stock Purchase Plan.
Sheli Z. Rosenberg, By: T. Richard Riney Attorney-in-Fact
2003-07-02