-----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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 SruTZuPN438NcLnkIElcOw==

<SEC-DOCUMENT>0000853816-06-000096.txt : 20060821
<SEC-HEADER>0000853816-06-000096.hdr.sgml : 20060821
<ACCEPTANCE-DATETIME>20060821163602
ACCESSION NUMBER:		0000853816-06-000096
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060817
FILED AS OF DATE:		20060821
DATE AS OF CHANGE:		20060821

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			LANDSTAR SYSTEM INC
		CENTRAL INDEX KEY:			0000853816
		STANDARD INDUSTRIAL CLASSIFICATION:	TRUCKING (NO LOCAL) [4213]
		IRS NUMBER:				061313069
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1226

	BUSINESS ADDRESS:	
		STREET 1:		13410 SUTTON PARK DRIVE SOUTH
		CITY:			JACKSONVILLE
		STATE:			FL
		ZIP:			32224
		BUSINESS PHONE:		9043901234

	MAIL ADDRESS:	
		STREET 1:		LANDSTAR SYSTEM INC
		STREET 2:		13410 SUTTON PARK DRIVE SOUTH
		CITY:			JACKSONVILLE
		STATE:			FL
		ZIP:			32224

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Beacom Joseph J
		CENTRAL INDEX KEY:			0001347776

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21238
		FILM NUMBER:		061046520

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		904-398-9400

	MAIL ADDRESS:	
		STREET 1:		13410 SUTTON PARK DRIVE SOUTH
		CITY:			JACKSONVILLE
		STATE:			FL
		ZIP:			32224
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-08-17</periodOfReport>

    <issuer>
        <issuerCik>0000853816</issuerCik>
        <issuerName>LANDSTAR SYSTEM INC</issuerName>
        <issuerTradingSymbol>LSTR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001347776</rptOwnerCik>
            <rptOwnerName>Beacom Joseph J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>13410 SUTTON PARK DRIVE SOUTH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>JACKSONVILLE</rptOwnerCity>
            <rptOwnerState>FL</rptOwnerState>
            <rptOwnerZipCode>32224</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, Chief Safety Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-08-17</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>800</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>44.51</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <ownerSignature>
        <signatureName>James B. Gattoni, Attorney-in-fact</signatureName>
        <signatureDate>2006-08-21</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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