EXHIBIT 15.1 LETTER RE: UNAUDITED INTERIM FINANCIAL INFORMATION

Board of Directors and Shareholders

STERIS Corporation

We are aware of the incorporation by reference in the following Registration Statements and related Prospectuses of our report dated January 22, 2001, relating to the unaudited consolidated interim
financial statements of STERIS Corporation and Subsidiaries that are included in its Form 10-Q for the quarter ended December 31, 2000:



|Registration

Number |  | Description                                                                                                                                                                                                        |  | Filing Date      
|-------------------- |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |  | -----------------
|                     |  |                                                                                                                                                                                                                    |  |                  
|333-40082            |  | Form S-8 Registration Statement -- Nonqualified Stock Option Agreement between STERIS Corporation and Laurie Brlas and the Nonqualified Stock Option Agreement between STERIS Corporation and David L.
Crandall    |  | June 26, 2000    
|333-40058            |  | Form S-8 Registration Statement -- Nonqualified Stock Option Agreement between STERIS Corporation and Les C. Vinney                                                                                                |  | June 23, 2000    
|333-65155            |  | Form S-8 Registration Statement -- STERIS Corporation Long Term Incentive Stock Plan                                                                                                                               |  | October 1, 1998  
|333-55839            |  | Form S-8 Registration Statement -- Nonqualified Stock Option Agreement between STERIS Corporation and John Masefield and the Nonqualified Stock Option Agreement between STERIS Corporation and Thomas
J. DeAngelo |  | June 2, 1998     
|333-32005            |  | Form S-8 Registration Statement -- STERIS Corporation 1997 Stock Option Plan                                                                                                                                       |  | July 24, 1997    
|333-06529            |  | Form S-3 Registration Statement -- STERIS Corporation                                                                                                                                                              |  | June 21, 1996    
|333-01610            |  | Post-effective Amendment to Form S-4 on Form S-8 -- STERIS Corporation                                                                                                                                             |  | May 16, 1996     
|33-91444             |  | Form S-8 Registration Statement -- STERIS Corporation 1994 Equity Compensation Plan                                                                                                                                |  | April 24, 1995   
|33-91442             |  | Form S-8 Registration Statement -- STERIS Corporation 1994 Nonemployee Directors Equity Compensation Plan                                                                                                          |  | April 24, 1995   
|33-55976             |  | Form S-8 Registration Statement -- STERIS Corporation 401(k)Plan                                                                                                                                                   |  | December 21, 1992
|33-55258             |  | Form S-8 Registration Statement -- STERIS Corporation Amended and Restated Non-Qualified Stock Option Plan                                                                                                         |  | December 4, 1992 

| | /s/ Ernst & Young LLP
| | ---------------------

Cleveland, Ohio

February 8, 2001