EXHIBIT 31.1

      Rule 13a-14(a)/15d-14(a) Certification of the Chief Executive Officer

I, Peter Wirth, Chairman of the Board of Directors and Chief Executive Officer
of Rofin-Sinar Technologies, Inc., certify that:

1. I have reviewed this annual report on Form 10-K of Rofin-Sinar Technologies
   Inc.

2. Based on my knowledge, this annual 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.

3. Based on my knowledge, the financial statements, and other financial
   information included in this annual 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 annual report.

4. The registrant'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 registrant and have:

   a) designed such disclosure controls and procedures, or caused such
      disclosure controls and procedures to be designed, 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 report is being prepared;

   b) evaluated the effectiveness of the registrant's disclosure controls and
      procedures presented in this report our conclusions about the
      effectiveness of the disclosure controls and procedures, as of the end of
      the period covered by this report, based on such evaluation; and

   c) disclosed in this report any change in the registrant's internal control
      over financial reporting that occurred during the registrant's most recent
      fiscal quarter (the registrant's fourth fiscal quarter in the case of an
      annual report) that has materially affected, or is reasonably likely to
      materially affect, the registrant's internal control over financial
      reporting; and

5. The registrant's other certifying officer(s) and I have disclosed, based on
   our most recent evaluation of internal control over financial reporting, to
   the registrant's auditors and the audit committee of registrant's board of
   directors (or persons performing the equivalent functions):

   a) all significant deficiencies and material weaknesses in the design or
      operation of internal control over financial reporting which are
      reasonably likely to adversely affect the registrant's ability to record,
      process, summarize and report financial information; and

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


Date:   December 19, 2003


                                                 /s/  Peter Wirth
                                                -----------------------
                                                Peter Wirth
                                                Chief Executive Officer