-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 U1jEg5SvVIBtM+XFcxrrNlU8RmLqKSp0J+JZLBh1vkCNB1cP/xuKB69RVbpqeTuk
 sXQoED+/x/e3LJwLKvWVew==

<SEC-DOCUMENT>0000704051-08-000113.txt : 20080723
<SEC-HEADER>0000704051-08-000113.hdr.sgml : 20080723
<ACCEPTANCE-DATETIME>20080723150823
ACCESSION NUMBER:		0000704051-08-000113
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080721
FILED AS OF DATE:		20080723
DATE AS OF CHANGE:		20080723

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Dewhurst Ronald R
		CENTRAL INDEX KEY:			0001427749

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08529
		FILM NUMBER:		08965677

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		410-539-0000

	MAIL ADDRESS:	
		STREET 1:		C/O LEGG MASON, INC.
		STREET 2:		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 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>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-07-21</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001427749</rptOwnerCik>
            <rptOwnerName>Dewhurst Ronald R</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O LEGG MASON, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>100 LIGHT STREET</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>Senior Managing Director</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-07-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>9850</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>11361</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>33.97</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2008-07-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>35000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2009-07-23</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2016-07-22</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>35000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>35000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Employee stock options vest serially over 5 years commencing on July 23, 2009.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Erin L. Clark, Attorney-in-fact for      Ronald R. Dewhurst</signatureName>
        <signatureDate>2008-07-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----