<?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>0001213928</rptOwnerCik>
            <rptOwnerName>GELLERT JAY M</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>7518.166</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 Reportig Person also owns options to purchase 20,000 shares of the Issuer's common stock.</footnote><footnote id="F2">Includes 127.150 shares acquired on June 24, 2003 under the Ventas, Inc. Distribution Reinvestment and Stock Purchase Plan.</footnote></footnotes><ownerSignature><signatureName>Jay M. Gellert, 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
0001213928
GELLERT JAY M
1
0
0
0
Common Stock
2003-07-01
4
A
0
494
15.18
A
7518.166
D
As of July 1, 2003 Reportig Person also owns options to purchase 20,000 shares of the Issuer's common stock.
Includes 127.150 shares acquired on June 24, 2003 under the Ventas, Inc. Distribution Reinvestment and Stock Purchase Plan.
Jay M. Gellert, By: T. Richard Riney Attorney-in-Fact
2003-07-02