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

    <documentType>4</documentType><periodOfReport>2004-01-05</periodOfReport>
    <issuer>
        <issuerCik>0000740260</issuerCik>
        <issuerName>VENTAS INC</issuerName>
        <issuerTradingSymbol>VTR</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001042563</rptOwnerCik>
            <rptOwnerName>THEOBALD THOMAS C</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>227 WEST MONROE, STE. 3500</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>CHICAGO</rptOwnerCity>
            <rptOwnerState>IL</rptOwnerState>
            <rptOwnerZipCode>60606</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeTable><derivativeTransaction><securityTitle><value>Stock Option (Right to Buy)</value></securityTitle><conversionOrExercisePrice><value>22.15</value></conversionOrExercisePrice><transactionDate><value>2004-01-05</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>5000</value><footnoteId id="F1"/></transactionShares><transactionPricePerShare><value>22.15</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2004-01-05</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2014-01-05</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>5000</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>15000</value><footnoteId id="F3"/><footnoteId id="F4"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></derivativeTransaction></derivativeTable><footnotes><footnote id="F1">Options granted pursuant to the Ventas, Inc. 2000 Stock Option Plan for Directors.</footnote><footnote id="F2">The options are exercisable in cumulative 50% annual installments beginning on 1/5/04.</footnote><footnote id="F3">Represents the total number of unexercised stock options held by Mr. Theobald as of January 5, 2004.</footnote><footnote id="F4">As of January 5, 2004, Reporting Person also owns 5,000 shares of Issuer's common stock.</footnote></footnotes><remarks/><ownerSignature><signatureName>Thomas C. Theobald, By: T. Richard Riney, Attorney-In-Fact</signatureName><signatureDate>2004-01-07</signatureDate></ownerSignature></ownershipDocument>
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X0201
4
2004-01-05
0000740260
VENTAS INC
VTR
0001042563
THEOBALD THOMAS C
227 WEST MONROE, STE. 3500
CHICAGO
IL
60606
1
0
0
0
Stock Option (Right to Buy)
22.15
2004-01-05
4
A
0
5000
22.15
A
2004-01-05
2014-01-05
Common Stock
5000
15000
D
Options granted pursuant to the Ventas, Inc. 2000 Stock Option Plan for Directors.
The options are exercisable in cumulative 50% annual installments beginning on 1/5/04.
Represents the total number of unexercised stock options held by Mr. Theobald as of January 5, 2004.
As of January 5, 2004, Reporting Person also owns 5,000 shares of Issuer's common stock.
Thomas C. Theobald, By: T. Richard Riney, Attorney-In-Fact
2004-01-07