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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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 qsJ7QEa5a2liaya11uoFdQ==

<SEC-DOCUMENT>0001195948-04-000009.txt : 20041202
<SEC-HEADER>0001195948-04-000009.hdr.sgml : 20041202
<ACCEPTANCE-DATETIME>20041202152000
ACCESSION NUMBER:		0001195948-04-000009
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20041130
FILED AS OF DATE:		20041202
DATE AS OF CHANGE:		20041202

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			BUSSE KEITH E
		CENTRAL INDEX KEY:			0001195948

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21719
		FILM NUMBER:		041180456

	MAIL ADDRESS:	
		STREET 1:		6714 POINTE INVERNESS WAY
		CITY:			FORT WAYNE
		STATE:			IN
		ZIP:			46804

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			STEEL DYNAMICS INC
		CENTRAL INDEX KEY:			0001022671
		STANDARD INDUSTRIAL CLASSIFICATION:	STEEL WORKS, BLAST FURNACES  ROLLING MILLS (COKE OVENS) [3312]
		IRS NUMBER:				351929476
		STATE OF INCORPORATION:			IN
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		6714 POINTE INVERNESS WAY
		STREET 2:		SUITE 200
		CITY:			FORT WAYNE
		STATE:			IN
		ZIP:			46804
		BUSINESS PHONE:		2604593553

	MAIL ADDRESS:	
		STREET 1:		6714 POINTE INVERNESS WAY
		STREET 2:		SUITE 200
		CITY:			FORT WAYNE
		STATE:			IN
		ZIP:			46804
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
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    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2004-11-30</periodOfReport>

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        <issuerCik>0001022671</issuerCik>
        <issuerName>STEEL DYNAMICS INC</issuerName>
        <issuerTradingSymbol>STLD</issuerTradingSymbol>
    </issuer>

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        <reportingOwnerId>
            <rptOwnerCik>0001195948</rptOwnerCik>
            <rptOwnerName>BUSSE KEITH E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>11522 WEST SYCAMORE HILLS DRIVE</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>FORT WAYNE</rptOwnerCity>
            <rptOwnerState>IN</rptOwnerState>
            <rptOwnerZipCode>46814</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
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        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>President and CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

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                <value>Common Stock</value>
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            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
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            <ownershipNature>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <transactionDate>
                <value>2004-11-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>800</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.81</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>561207</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
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                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <transactionDate>
                <value>2004-11-30</value>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>9000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.82</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>552207</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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                <natureOfOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <transactionDate>
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            <transactionCoding>
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                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5600</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.83</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
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        </nonDerivativeTransaction>
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                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>1500</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.84</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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                <sharesOwnedFollowingTransaction>
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                <transactionShares>
                    <value>3800</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.85</value>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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                <sharesOwnedFollowingTransaction>
                    <value>541307</value>
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                <directOrIndirectOwnership>
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        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
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                <value>Common Stock</value>
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            <transactionDate>
                <value>2004-11-30</value>
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                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.87</value>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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                <directOrIndirectOwnership>
                    <value>D</value>
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                    <value></value>
                </natureOfOwnership>
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        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
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            <transactionDate>
                <value>2004-11-30</value>
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                <transactionShares>
                    <value>1044</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>40.89</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>535263</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Keith E. Busse</signatureName>
        <signatureDate>2004-12-01</signatureDate>
    </ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----