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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 JkqUB5axRrvk7mddmZjYMx0+5TCploN3DIqxQLJWAKYBiVMqhrzCr8s3XnRwHTWV
 fvg+iP+d0i5DuAdlMME2qw==

<SEC-DOCUMENT>0000745981-09-000059.txt : 20091218
<SEC-HEADER>0000745981-09-000059.hdr.sgml : 20091218
<ACCEPTANCE-DATETIME>20091218174700
ACCESSION NUMBER:		0000745981-09-000059
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20091217
FILED AS OF DATE:		20091218
DATE AS OF CHANGE:		20091218

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			PUMPELLY R GLENN
		CENTRAL INDEX KEY:			0001274402

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-11826
		FILM NUMBER:		091251052

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MIDSOUTH BANCORP INC
		CENTRAL INDEX KEY:			0000745981
		STANDARD INDUSTRIAL CLASSIFICATION:	NATIONAL COMMERCIAL BANKS [6021]
		IRS NUMBER:				721020809
		STATE OF INCORPORATION:			LA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		102 VERSAILLES BLVD
		STREET 2:		VERSAILLES CENTRE
		CITY:			LAFAYETTE
		STATE:			LA
		ZIP:			70501
		BUSINESS PHONE:		3182378343

	MAIL ADDRESS:	
		STREET 1:		102 VERSAILLES BLVD
		CITY:			LAFAYETTE
		STATE:			LA
		ZIP:			70501
</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>2009-12-17</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000745981</issuerCik>
        <issuerName>MIDSOUTH BANCORP INC</issuerName>
        <issuerTradingSymbol>MSL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001274402</rptOwnerCik>
            <rptOwnerName>PUMPELLY R GLENN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>102 VERSAILLES BLVD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>LAFAYETTE</rptOwnerCity>
            <rptOwnerState>LA</rptOwnerState>
            <rptOwnerZipCode>70501</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2009-12-17</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>12.75</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>22279</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>R. Glenn Pumpelly</signatureName>
        <signatureDate>2009-12-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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