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 20, 2003, 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, 2002:



|Registration Number |  | Description                                                                                                                                                                                                    
|------------------- |  | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|                   
|333-101308          |  | Form S-8 Registration StatementSTERIS Corporation 2002 Stock Option
Plan                                                                                                                                      
|                   
|333-91302           |  | Form S-8 Registration StatementNonqualified Stock Option Agreement between STERIS Corporation and Mark. D.
McGinley                                                                                           
|                   
|333-63774           |  | Form S-8 Registration StatementNonqualified Stock Option Agreement between STERIS Corporation and Peter A.
Burke                                                                                              
|                   
|333-63772           |  | Form S-8 Registration StatementNonqualified Stock Option Agreement between STERIS Corporation and Thomas J.
Magulski                                                                                          
|                   
|333-63770           |  | Form S-8 Registration StatementNonqualified Stock Option Agreement between STERIS Corporation and Charles L.
Immel and Restricted Shares Agreement between STERIS Corporation and Charles L. Immel            
|                   
|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   
|                   
|333-40058           |  | Form S-8 Registration StatementNonqualified Stock Option Agreement between STERIS Corporation and Les C.
Vinney                                                                                               
|                   
|333-65155           |  | Form S-8 Registration StatementSTERIS Corporation 1998 Long Term Incentive
Compensation Plan                                                                                                                  
|                   
|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
|                   
|333-32005           |  | Form S-8 Registration StatementSTERIS Corporation 1997 Stock Option
Plan                                                                                                                                      
|                   
|333-06529           |  | Form S-3 Registration StatementSTERIS Corporation                                                                                                                                                             
|                   
|333-01610           |  | Post-effective Amendment to Form S-4 on Form S-8STERIS
Corporation                                                                                                                                            
|                   
|33-91444            |  | Form S-8 Registration StatementSTERIS Corporation 1994 Equity Compensation
Plan                                                                                                                               
|                   
|33-91442            |  | Form S-8 Registration StatementSTERIS Corporation 1994 Nonemployee Directors
Equity Compensation Plan                                                                                                         
|                   
|33-55976            |  | Form S-8 Registration StatementSTERIS Corporation 401(k)
Plan                                                                                                                                                 
|                   
|33-55258            |  | Form S-8 RegistrationSTERIS Corporation Amended and Restated Non-Qualified
Stock Option                                                                                                                       



/s/ ERNST & YOUNG LLP



Cleveland, Ohio

February 12, 2003