-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 LKgqbl458JKsCjGTJy6Nt1oE3rpf6kdPLpwJsqTbL/XJE70xassMIzEUNOYG4PHU
 FL22EqUxZMCSKY2xdTzL+Q==

<SEC-DOCUMENT>0000931017-04-000021.txt : 20040729
<SEC-HEADER>0000931017-04-000021.hdr.sgml : 20040729
<ACCEPTANCE-DATETIME>20040729160313
ACCESSION NUMBER:		0000931017-04-000021
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20040729
FILED AS OF DATE:		20040729

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NBTY INC
		CENTRAL INDEX KEY:			0000070793
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				112228617
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		90 ORVILLE DR
		CITY:			BOHEMIA
		STATE:			NY
		ZIP:			11716
		BUSINESS PHONE:		5165679500

	MAIL ADDRESS:	
		STREET 1:		90 ORVILLE DRIVE
		CITY:			BOHEMIA
		STATE:			NY
		ZIP:			11716

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	NATURES BOUNTY INC
		DATE OF NAME CHANGE:	19920703

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ASHNER MICHAEL L
		CENTRAL INDEX KEY:			0001139233

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-31788
		FILM NUMBER:		04939207

	BUSINESS ADDRESS:	
		STREET 1:		C/O WINTHROP FINANCIAL ASSOCIATES
		STREET 2:		100 JERICHO QUADRANGLE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			11753
		BUSINESS PHONE:		5168220022

	MAIL ADDRESS:	
		STREET 1:		C/O WINTHROP FINANCIAL ASSOCIATES
		STREET 2:		100 JERICHO QUADRANGLE
		CITY:			NEW YORK
		STATE:			NY
		ZIP:			11753
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-07-29</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000070793</issuerCik>
        <issuerName>NBTY INC</issuerName>
        <issuerTradingSymbol>nty</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001139233</rptOwnerCik>
            <rptOwnerName>ASHNER MICHAEL L</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O WINTHROP FINANCIAL ASSOCIATES</rptOwnerStreet1>
            <rptOwnerStreet2>TWO JERICHO PLAZA WING A</rptOwnerStreet2>
            <rptOwnerCity>JERICHO</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>11753</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares</value>
            </securityTitle>
            <transactionDate>
                <value>2004-07-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>20.7166</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>45000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>Michael L. Ashner</signatureName>
        <signatureDate>2004-07-29</signatureDate>
    </ownerSignature>
</ownershipDocument>

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