EXHIBIT 31.1

                      CHIEF EXECUTIVE OFFICER CERTIFICATION
                     REQUIRED BY ITEM 307 OF REGULATION S-K
            AS PROMULGATED BY THE SECURITIES AND EXCHANGE COMMISSION
            PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002

I, Keith E. Busse, President and Chief Executive Officer, certify that:

        1. I have reviewed this quarterly report on Form 10-Q of Steel Dynamics,
Inc.;

        2. Based on my knowledge, this quarterly report does not contain any
untrue statement of a material fact or omit to state a material fact necessary
to make the statements made, in light of the circumstances under which such
statements were made, not misleading with respect to the period covered by this
quarterly report;

        3. Based on my knowledge, the financial statements, and other financial
information included in this quarterly report, fairly present in all material
respects the financial condition, results of operations and cash flows of the
registrant as of, and for, the periods presented in this quarterly report;

        4. The registrant's other certifying officer and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-14 and 15d-14 for the registrant and have:

           a.   Designed such disclosure controls and procedures to ensure that
                material information relating to the registrant, including its
                consolidated subsidiaries, is made known to us by others within
                those entities, particularly during the period in which this
                quarterly report is being prepared;

           b.   Evaluated the effectiveness of the registrant's disclosure
                controls and procedures as of a date within 90 days prior to the
                filing date of this quarterly report (the "Evaluation Date");
                and

           c.   Presented in this quarterly report our conclusions about the
                effectiveness of the disclosure controls and procedures based on
                our evaluation as of the Evaluation Date;

        5. The registrant's other certifying officers and I have disclosed,
based on our most recent evaluation, to the registrant's auditors and the audit
committee of registrant's board of directors:

           a.   All significant deficiencies in the design or operation of
                internal controls which could adversely affect the registrant's
                ability to record, process, summarize and report financial data
                and have identified for the registrant's auditors any material
                weaknesses in internal controls; and

           b.   any fraud, whether or not material, that involves management or
                other employees who have a significant role in the registrant's
                internal controls over financial reporting.

          /s/ KEITH E. BUSSE
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Keith E. Busse
President and Chief Executive Officer
November 8, 2004