<SEC-DOCUMENT>0001140361-14-008133.txt : 20140214
<SEC-HEADER>0001140361-14-008133.hdr.sgml : 20140214
<ACCEPTANCE-DATETIME>20140214193245
ACCESSION NUMBER:		0001140361-14-008133
CONFORMED SUBMISSION TYPE:	5
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110404
FILED AS OF DATE:		20140214
DATE AS OF CHANGE:		20140214

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			FOSTER L B CO
		CENTRAL INDEX KEY:			0000352825
		STANDARD INDUSTRIAL CLASSIFICATION:	WHOLESALE-METALS SERVICE CENTERS & OFFICES [5051]
		IRS NUMBER:				251324733
		STATE OF INCORPORATION:			PA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		415 HOLIDAY DR
		CITY:			PITTSBURGH
		STATE:			PA
		ZIP:			15220
		BUSINESS PHONE:		4129283431

	MAIL ADDRESS:	
		STREET 1:		415 HOLIDAY DR
		CITY:			PITTSBURGH
		STATE:			PA
		ZIP:			15220

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			FISHER SAMUEL K
		CENTRAL INDEX KEY:			0001215497

	FILING VALUES:
		FORM TYPE:		5
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-10436
		FILM NUMBER:		14619816
</SEC-HEADER>
<DOCUMENT>
<TYPE>5
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 5
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        <issuerTradingSymbol>FSTR</issuerTradingSymbol>
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            <rptOwnerStreet2>415 HOLIDAY DRIVE</rptOwnerStreet2>
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            <rptOwnerState>PA</rptOwnerState>
            <rptOwnerZipCode>15220</rptOwnerZipCode>
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            <officerTitle>Vice President</officerTitle>
            <otherText></otherText>
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                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeHolding>
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                <value>Common Stock</value>
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                <transactionFormType></transactionFormType>
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                <sharesOwnedFollowingTransaction>
                    <value>1779</value>
                    <footnoteId id="F1"/>
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                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401(k)</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Between August 27, 2013 and December 31, 2013, the reporting person acquired 3 shares of the Company's common stock under the 401(k) plan.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Samuel K. Fisher by Deborah J. Foster, attorney-in-fact</signatureName>
        <signatureDate>2014-02-14</signatureDate>
    </ownerSignature>
</ownershipDocument>
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</SEC-DOCUMENT>
