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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 MTVxnoYyIhLn8E694YQsLw==

<SEC-DOCUMENT>0001459765-09-000001.txt : 20091103
<SEC-HEADER>0001459765-09-000001.hdr.sgml : 20091103
<ACCEPTANCE-DATETIME>20091103152440
ACCESSION NUMBER:		0001459765-09-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20091030
FILED AS OF DATE:		20091103
DATE AS OF CHANGE:		20091103

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Nattans Jeffrey A
		CENTRAL INDEX KEY:			0001459765

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08529
		FILM NUMBER:		091154302

	MAIL ADDRESS:	
		STREET 1:		100 LIGHT STREET
		CITY:			BALTIMORE
		STATE:			MD
		ZIP:			21202

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LEGG MASON INC
		CENTRAL INDEX KEY:			0000704051
		STANDARD INDUSTRIAL CLASSIFICATION:	INVESTMENT ADVICE [6282]
		IRS NUMBER:				521200960
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		100 INTERNATIONAL DRIVE
		CITY:			BALTIMORE
		STATE:			MD
		ZIP:			21202
		BUSINESS PHONE:		4105390000

	MAIL ADDRESS:	
		STREET 1:		100 INTERNATIONAL DRIVE
		CITY:			BALTIMORE
		STATE:			MD
		ZIP:			21202
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-10-30</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000704051</issuerCik>
        <issuerName>LEGG MASON INC</issuerName>
        <issuerTradingSymbol>LM</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001459765</rptOwnerCik>
            <rptOwnerName>Nattans Jeffrey A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>100 INTERNATIONAL DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BALTIMORE</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>21202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice President</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>30851</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-10-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>4.37</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>28.81</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stck</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>4.37</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4195.91</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Includes the acquisition of 301.22 shares of Legg Mason, Inc. Common Stock pursuant to the Legg Mason, Inc. Employee Stock Purchase Plan from August 4, 2009 to October 26, 2009 at prices ranging from $26.71 to $32.82.</footnote>
        <footnote id="F2">Phantom Stock Units acquired purusant to and under the conditions of the Legg Mason &amp; Co., LLC Deferred Compensation/Phantom Stock Plan, as amended.  See Exhibit 10.4 of Form 10-K for the fiscal year ended March 31, 2009.</footnote>
        <footnote id="F3">1-for-1</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Erin L. Clark, Attorney-in-fact for Jeffrey A. Nattans</signatureName>
        <signatureDate>2009-11-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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