-----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,
 V1J/RGFsNFx2MNiWWsCsjqqou7d5bxlyyQ7dEGo4GnlUuwOo6WpRPks56qVl1k+0
 eouvFds/YFJt9hRnhrkdZQ==

<SEC-DOCUMENT>0001195955-03-000001.txt : 20030523
<SEC-HEADER>0001195955-03-000001.hdr.sgml : 20030523
<ACCEPTANCE-DATETIME>20030523163130
ACCESSION NUMBER:		0001195955-03-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030523
FILED AS OF DATE:		20030523

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			HIDAKA NAOKI
		CENTRAL INDEX KEY:			0001195955

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21719
		FILM NUMBER:		03718446

	MAIL ADDRESS:	
		STREET 1:		6714 POINTE INVERNESS WAY
		STREET 2:		SUITE 200
		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:		7030 POINTE INVERNESS WAY
		STREET 2:		SUITE 310
		CITY:			FORT WAYNE
		STATE:			IN
		ZIP:			46804
		BUSINESS PHONE:		2194593553

	MAIL ADDRESS:	
		STREET 1:		7030 POINTE INVERNERSS WAY
		STREET 2:		SUITE 310
		CITY:			FORT WAYNE
		STATE:			IN
		ZIP:			46804
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-05-23</periodOfReport>
    <issuer>
        <issuerCik>0001022671</issuerCik>
        <issuerName>STEEL DYNAMICS INC</issuerName>
        <issuerTradingSymbol>STLD</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001195955</rptOwnerCik>
            <rptOwnerName>HIDAKA NAOKI</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>0</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther></reportingOwnerRelationship></reportingOwner><derivativeSecurity><securityTitle><value>Non-Employee Director Stock Option (right to buy)</value><footnoteId id="F1"/></securityTitle><conversionOrExercisePrice><value>12.76</value></conversionOrExercisePrice><transactionDate><value>2003-05-21</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>1176</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2003-11-21</value></exerciseDate><expirationDate><value>2008-05-21</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecu
rityTitle><underlyingSecurityShares><value>1176</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>1176</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">Pursuant to Non-Employee Director Stock Option Plan approved by stockholders and exempt from Section 16(b) of the Securities and Exchange Act of 1934 pursuant to Rule 16b-3.</footnote></footnotes><ownerSignature><signatureName>Naoki Hidaka</signatureName><signatureDate>2003-05-23</signatureDate></ownerSignature></ownershipDocument>

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