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|Exhibit 32.1
Certification of Principal Executive OfficerPursuant to 18 U.S.C. 1350(Section 906 of the Sarbanes-Oxley Act of 2002)
I, David Unger, Chief Executive Officer (principal executive officer) of MFRI, Inc. (the Registrant),
certify that to the best of my knowledge, based upon a review of the Annual Report on Form 10-K for
the period ended January 31, 2005 of the Registrant (the Report):
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| | (1) | The Report fully complies with the requirements of Section 13(a) of the Securities Exchange Act of

1934, as amended; and                               
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| |     |                                                                                                                                                         
| | (2) | The information contained in the Report fairly presents, in all material respects, the financial condition

and results of operations of the Registrant.

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|/s/ David Unger                                                                                                                                                                                                                                                                                                                                            
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|David UngerDirector and Chairman of the Board of Directors,and Chief Executive Officer(Principal Executive Officer)April 29, 2005
A signed original of this written statement required by Section 906 has been provided to MFRI, Inc.
and will be retained by MFRI, Inc. and furnished to the Securities and Exchange Commission or its
staff upon request.

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