-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0001140361-10-043215.txt : 20101102
<SEC-HEADER>0001140361-10-043215.hdr.sgml : 20101102
<ACCEPTANCE-DATETIME>20101102170940
ACCESSION NUMBER:		0001140361-10-043215
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20101101
FILED AS OF DATE:		20101102
DATE AS OF CHANGE:		20101102

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			CUMMING IAN M.
		CENTRAL INDEX KEY:			0001213601

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-14947
		FILM NUMBER:		101158985

	MAIL ADDRESS:	
		STREET 1:		529 EAST SOUTH TEMPLE
		CITY:			SALT LAKE CITY
		STATE:			UT
		ZIP:			84102

	FORMER NAME:	
		FORMER CONFORMED NAME:	CUMMING IAN M
		DATE OF NAME CHANGE:	20030109

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			JEFFERIES GROUP INC /DE/
		CENTRAL INDEX KEY:			0001084580
		STANDARD INDUSTRIAL CLASSIFICATION:	SECURITY BROKERS, DEALERS & FLOTATION COMPANIES [6211]
		IRS NUMBER:				954719745
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1130

	BUSINESS ADDRESS:	
		STREET 1:		520 MADISON AVENUE
		STREET 2:		12TH FLOOR
		CITY:			NEW  YORK
		STATE:			NY
		ZIP:			10022
		BUSINESS PHONE:		212-284-2550

	MAIL ADDRESS:	
		STREET 1:		520 MADISON AVENUE
		STREET 2:		12TH FLOOR
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			10022

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	JEF HOLDING CO INC
		DATE OF NAME CHANGE:	19990419
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-11-01</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001084580</issuerCik>
        <issuerName>JEFFERIES GROUP INC /DE/</issuerName>
        <issuerTradingSymbol>JEF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001213601</rptOwnerCik>
            <rptOwnerName>CUMMING IAN M.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O LEUCADIA NATIONAL CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>315 PARK AVENUE SOUTH</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10010</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14547.953</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-11-01</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>75000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>23.449</value>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>49351385</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Explanation</value>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Reflects weighted average per share purchase price of separately priced transactions at a range of $23.39-$23.61. Upon the request of the Commission or a security holder of the issuer, full information regarding the number of shares purchased at each separate price will be provided to the requesting party.</footnote>
        <footnote id="F2">Reflects shares of Issuer's common stock beneficially owned by Leucadia National Corporation (&quot;Leucadia&quot;). The Reporting Person is a significant shareholder and Chairman of the Board of Leucadia.  The Reporting Person disclaims beneficial ownership of the Issuer's common stock owned beneficially by Leucadia, except to the extent of his pecuniary interest, if any.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Ian M. Cumming</signatureName>
        <signatureDate>2010-11-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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