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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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 N0CFCUzHTcazml8REGkfOQ==

<SEC-DOCUMENT>0001140361-11-013524.txt : 20110302
<SEC-HEADER>0001140361-11-013524.hdr.sgml : 20110302
<ACCEPTANCE-DATETIME>20110302165710
ACCESSION NUMBER:		0001140361-11-013524
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20110228
FILED AS OF DATE:		20110302
DATE AS OF CHANGE:		20110302

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			IGNACZAK EDWARD B
		CENTRAL INDEX KEY:			0001235677

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-20199
		FILM NUMBER:		11657043

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			EXPRESS SCRIPTS INC
		CENTRAL INDEX KEY:			0000885721
		STANDARD INDUSTRIAL CLASSIFICATION:	RETAIL-DRUG STORES AND PROPRIETARY STORES [5912]
		IRS NUMBER:				431420563
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		ONE EXPRESS WAY
		CITY:			ST LOUIS
		STATE:			MO
		ZIP:			63121
		BUSINESS PHONE:		3149960900

	MAIL ADDRESS:	
		STREET 1:		ONE EXPRESS WAY
		CITY:			ST LOUIS
		STATE:			MO
		ZIP:			63121
</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>2011-02-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000885721</issuerCik>
        <issuerName>EXPRESS SCRIPTS INC</issuerName>
        <issuerTradingSymbol>ESRX</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001235677</rptOwnerCik>
            <rptOwnerName>IGNACZAK EDWARD B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O EXPRESS SCRIPTS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>ONE EXPRESS WAY</rptOwnerStreet2>
            <rptOwnerCity>ST. LOUIS</rptOwnerCity>
            <rptOwnerState>MO</rptOwnerState>
            <rptOwnerZipCode>63121</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>EVP, Sales &amp; Marketing</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2011-02-28</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3791</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>56.22</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>70087</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents shares tendered to Express Scripts, Inc. to cover Reporting Person's tax liability due upon lapse of restrictions of restricted stock previously awarded under the Express Scripts, Inc. 2000 Long-Term Incentive Plan.</footnote>
        <footnote id="F2">Reporting Person's shares beneficially owned have been adjusted to reflect the Company's 2-for-1 stock split effective on June 7, 2010.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Edward Ignaczak</signatureName>
        <signatureDate>2011-03-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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