<SEC-DOCUMENT>0001179110-14-017689.txt : 20141205
<SEC-HEADER>0001179110-14-017689.hdr.sgml : 20141205
<ACCEPTANCE-DATETIME>20141205174448
ACCESSION NUMBER:		0001179110-14-017689
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20141125
FILED AS OF DATE:		20141205
DATE AS OF CHANGE:		20141205

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			ECOLAB INC
		CENTRAL INDEX KEY:			0000031462
		STANDARD INDUSTRIAL CLASSIFICATION:	SOAP, DETERGENT, CLEANING PREPARATIONS, PERFUMES, COSMETICS [2840]
		IRS NUMBER:				410231510
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		ECOLAB CORPORATE CENTER
		STREET 2:		370 WABASHA STREET NORTH
		CITY:			ST PAUL
		STATE:			MN
		ZIP:			55102
		BUSINESS PHONE:		6512932233

	MAIL ADDRESS:	
		STREET 1:		ECOLAB CORPORATE CENTER
		STREET 2:		370 WABASHA STREET NORTH
		CITY:			ST. PAUL
		STATE:			MN
		ZIP:			55102

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ECONOMICS LABORATORY INC
		DATE OF NAME CHANGE:	19861203

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			SEIFERT JAMES J
		CENTRAL INDEX KEY:			0001215481

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-09328
		FILM NUMBER:		141270569

	MAIL ADDRESS:	
		STREET 1:		C/O BEMIS CO INC
		STREET 2:		222 S. 9TH ST. #2300
		CITY:			MINNEAPOLIS
		STATE:			MN
		ZIP:			55402
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>FORM 4/A -
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2014-11-25</periodOfReport>

    <dateOfOriginalSubmission>2014-11-25</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000031462</issuerCik>
        <issuerName>ECOLAB INC</issuerName>
        <issuerTradingSymbol>ECL</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001215481</rptOwnerCik>
            <rptOwnerName>SEIFERT JAMES J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ECOLAB INC.</rptOwnerStreet1>
            <rptOwnerStreet2>370 WABASHA ST. N</rptOwnerStreet2>
            <rptOwnerCity>ST. PAUL</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55102</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Ex.VP, Gen. Counsel &amp; Secy.</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-11-25</value>
                <footnoteId id="F1"/>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>23100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>113.7466</value>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>25473</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On the initial Form 4, the transaction date was incorrectly reported as November 20, 2014 and this amendment is being filed to correct the transaction date to November 25, 2014.  This amendment only reports the transaction requiring correction from the initial Form 4 and does not repeat the other transactions reported on the initial Form 4 that do not require correction.</footnote>
        <footnote id="F2">This transaction was executed in multiple trades at prices ranging from $113.69 to $113.83. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the SEC staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>David F. Duvick, as Attorney-in-Fact for James J. Seifert</signatureName>
        <signatureDate>2014-12-05</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
