-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Gemf3boIx/gi13OQ/QtgJPbydLTCrmXGt2dblK8qINRm3Iby7pq5R5/GcmBgNDn/
 Pbr0Ccgoqyp9yEmtuJRufw==

<SEC-DOCUMENT>0001243411-03-000004.txt : 20031015
<SEC-HEADER>0001243411-03-000004.hdr.sgml : 20031013
<ACCEPTANCE-DATETIME>20031015124649
ACCESSION NUMBER:		0001243411-03-000004
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20031013
FILED AS OF DATE:		20031015

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			MUMA LARRY
		CENTRAL INDEX KEY:			0001243417

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-16612
		FILM NUMBER:		03941283

	MAIL ADDRESS:	
		STREET 1:		1312 SUMMIT OAKS DR
		CITY:			BURNSVILLE
		STATE:			MN
		ZIP:			55337

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CNS INC /DE/
		CENTRAL INDEX KEY:			0000814258
		STANDARD INDUSTRIAL CLASSIFICATION:	ELECTROMEDICAL & ELECTROTHERAPEUTIC APPARATUS [3845]
		IRS NUMBER:				411580270
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		PO BOX 39802
		CITY:			MINNEAPOLIS
		STATE:			MN
		ZIP:			55439
		BUSINESS PHONE:		6128206696

	MAIL ADDRESS:	
		STREET 1:		PO BOX 39802
		STREET 2:		PO BOX 39802
		CITY:			MINNEAPOLIS
		STATE:			MN
		ZIP:			55439
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>

<ownershipDocument>

    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2003-10-13</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000814258</issuerCik>
        <issuerName>CNS INC /DE/</issuerName>
        <issuerTradingSymbol>CNXS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001243417</rptOwnerCik>
            <rptOwnerName>MUMA LARRY</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1312 SUMMIT OAKS DR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>BURNSVILLE</rptOwnerCity>
            <rptOwnerState>MN</rptOwnerState>
            <rptOwnerZipCode>55337</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>VP, Operations</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>

        <derivativeTransaction>
            <securityTitle>
                <value>Stock Option</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>11.37</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2003-10-13</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>15000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>11.37</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2004-10-13</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2013-10-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>15000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>

    </derivativeTable>

    <footnotes>
        <footnote id="F1">Options vest equally over a 3-year period beginning 10/13/2004.</footnote>
    </footnotes>


    <ownerSignature>
        <signatureName>MichaelW. Weber, by power of attorney</signatureName>
        <signatureDate>2003-10-15</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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