-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 SzmkRKbWt5Xjb5ZrM98CrDBfnEia3f1zCsAV4YKsNJKUSMeI78lac3FVUX92Cmtq
 PQeddWMf4L99geG768YFuQ==

<SEC-DOCUMENT>0000704051-05-000191.txt : 20051201
<SEC-HEADER>0000704051-05-000191.hdr.sgml : 20051201
<ACCEPTANCE-DATETIME>20051201151232
ACCESSION NUMBER:		0000704051-05-000191
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20051129
FILED AS OF DATE:		20051201
DATE AS OF CHANGE:		20051201

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DALEY CHARLES J JR
		CENTRAL INDEX KEY:			0001206661

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08529
		FILM NUMBER:		051237516

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

	MAIL ADDRESS:	
		STREET 1:		LEGG MASON INC
		STREET 2:		100 LIGHT ST
		CITY:			BALTIMORE
		STATE:			MD
		ZIP:			21202

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LEGG MASON INC
		CENTRAL INDEX KEY:			0000704051
		STANDARD INDUSTRIAL CLASSIFICATION:	SECURITY BROKERS, DEALERS & FLOTATION COMPANIES [6211]
		IRS NUMBER:				521200960
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		100 LIGHT ST
		CITY:			BALTIMORE
		STATE:			MD
		ZIP:			21202-1476
		BUSINESS PHONE:		4105390000

	MAIL ADDRESS:	
		STREET 1:		100 LIGHT ST
		CITY:			BALTIMORE
		STATE:			MD
		ZIP:			21202-1476
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2005-11-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001206661</rptOwnerCik>
            <rptOwnerName>DALEY CHARLES J JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>LEGG MASON INC</rptOwnerStreet1>
            <rptOwnerStreet2>100 LIGHT ST</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>Sr. VP, CFO &amp; Treas.</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>12584.35</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to buy)</value>
                <footnoteId id="F2"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>122.91</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2005-11-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-07-23</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-07-22</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>10000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>10000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Acquisition of 2.756 shares of Common Stock pursuant to the Legg Mason, Inc. Employee Stock Purchase Plan from October 20, 2005 to November 29, 2005 at prices ranging from $104.75 to $121.77.</footnote>
        <footnote id="F2">Stock options vest serially over five years commencing on July 23, 2006.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Erin L. Clark, Attorney-in-fact for Charles J. Daley, Jr.</signatureName>
        <signatureDate>2005-12-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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