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Exhibit 12.1

CERTIFICATION UNDER SECTION 302 
OF THE U.S. SARBANES-OXLEY ACT OF 2002

I, José Armando de Figueiredo Campos, certify that:

|1. | I have reviewed this annual report on Form 20-F of Arcelor Brasil S.A. (the company);                                                                                                                                                                                                                     
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|2. | Based on my knowledge, this 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 report;
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|3. | Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the company as of, and for, the
  periods presented in this report;                      
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|4. | The companys other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the company and have:                                                                                    
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|   | (a)                                                                                                                                                                                                                                                                                                         
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|   | (b)                                                                                                                                                                                                                                                                                                         
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|   | (c)                                                                                                                                                                                                                                                                                                         
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|5. | The companys other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the companys auditors and the audit committee of the companys board of directors
  (or persons performing the equivalent functions):                 
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|   | (a)                                                                                                                                                                                                                                                                                                         
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|   | (b)                                                                                                                                                                                                                                                                                                         
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/s/ José Armando de Figueiredo Campos 
José Armando de Figueiredo Campos 
Chief Executive Officer 
June 29, 2006