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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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 xgjrREg4vQSMibS3RdvsqQ==

<SEC-DOCUMENT>0001140361-10-025536.txt : 20100615
<SEC-HEADER>0001140361-10-025536.hdr.sgml : 20100615
<ACCEPTANCE-DATETIME>20100615143046
ACCESSION NUMBER:		0001140361-10-025536
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100611
FILED AS OF DATE:		20100615
DATE AS OF CHANGE:		20100615

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Castro Renato A
		CENTRAL INDEX KEY:			0001483619

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-07615
		FILM NUMBER:		10897144

	MAIL ADDRESS:	
		STREET 1:		55 WAUGH DRIVE
		STREET 2:		SUITE 1000
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77007

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			KIRBY CORP
		CENTRAL INDEX KEY:			0000056047
		STANDARD INDUSTRIAL CLASSIFICATION:	WATER TRANSPORTATION [4400]
		IRS NUMBER:				741884980
		STATE OF INCORPORATION:			NV
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		55 WAUGH DRIVE SUITE 1000
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77385
		BUSINESS PHONE:		7134351000

	MAIL ADDRESS:	
		STREET 1:		P.O. BOX 1745
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77251

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	KIRBY EXPLORATION CO INC
		DATE OF NAME CHANGE:	19900510
</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>2010-06-11</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000056047</issuerCik>
        <issuerName>KIRBY CORP</issuerName>
        <issuerTradingSymbol>KEX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001483619</rptOwnerCik>
            <rptOwnerName>Castro Renato A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>55 WAUGH DRIVE, SUITE 1000</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77007</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Treasurer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, par value $.10 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2010-06-11</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>378</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>38.77</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>4076</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock, par value $.10 per share</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>341</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>401K Plan</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>G. Stephen Holcomb, Agent and Attorney-in-Fact</signatureName>
        <signatureDate>2010-06-15</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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