EXHIBIT 10.1

AMENDMENT NO. 1 TO CREDIT AGREEMENT

            This Amendment No. 1 to Credit Agreement (this “ Amendment ”) is
made as of July 25, 2002, by and among STERIS CORPORATION, an Ohio corporation
(“ Borrower ”), the lending institutions parties to the Credit Agreement, as
hereinafter defined (“ Lenders ”), and KEYBANK NATIONAL ASSOCIATION, as
administrative agent for the Lenders (“ Agent ”).

RECITALS:

            A.   Borrower, Agent and the Lenders are parties to the Credit
Agreement, dated as of March 28, 2002 (as the same may from time to time be
amended, restated or otherwise modified, the “ Credit Agreement ”).

            B.   Borrower, Agent and the Lenders desire to amend the Credit
Agreement to modify certain provisions thereof.

            C.   Each capitalized term used herein shall be defined in
accordance with the Credit Agreement.

AGREEMENT:

            In consideration of the premises and mutual covenants herein and for
other valuable considerations, Borrower, Agent and the Lenders agree as follows:

            1.    New Definitions . Section 1.1 of the Credit Agreement is
hereby amended to add the following new definitions thereto:

        “ General Share Repurchase ” means any Share Repurchase other than a
Special Share Repurchase.

        “ General Share Repurchase Limit ” means the lesser of (i) $125,000,000
minus the aggregate amount of Special Share Repurchases, or (ii) $65,000,000.

        “ Special Share Repurchase ” means any Share Repurchase made by Borrower
during the period from June 27, 2002 through October 25, 2002, inclusive.

        “ Special Share Repurchase Limit ” means $125,000,000.

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            2.    Amendment to Definitions . Section 1.1 of the Credit Agreement
is hereby amended to delete the definition of “ Consolidated Net Worth ”
therefrom and to insert in place thereof the following:

        “ Consolidated Net Worth ” means, at any date, the stockholders’ equity
of Borrower, determined on a Consolidated basis and in accordance with GAAP;
provided, however that, for the purposes of calculating Consolidated Net Worth
under Section 5.07(c) hereof for any period ending on or after June 30, 2002, an
amount equal to the aggregate amount of all Special Share Repurchases (which,
but for this proviso, would have the effect of reducing stockholders’ equity)
shall be added back to stockholders’ equity in determining Consolidated Net
Worth.

            3.    Amendment to Share Repurchases Covenant . Section 5.14 of the
Credit Agreement is hereby amended and restated in its entirety as follows:

        Section 5.14.    Share Repurchases . Borrower shall not make any Share
Repurchase; provided, however, that, so long as no Default or Event of Default
exists or would exist immediately thereafter, Borrower (a) may make Special
Share Repurchases so long as the aggregate amount of Special Share Repurchases
made since the Closing Date does not at any time exceed the Special Share
Repurchase Limit, and (b) may make General Share Repurchases so long as the
aggregate amount of General Share Repurchases made since the Closing Date does
not at any time exceed the General Share Repurchase Limit.

            4.    Conditions Precedent . The amendments set forth above shall
become effective upon the satisfaction of the following conditions precedent:

            (a)   Borrower shall cause each Guarantor of Payment to consent and
agree to and acknowledge the terms of this Amendment;

            (b)   Borrower shall provide such other items and shall satisfy such
other conditions as may be reasonably required by Agent and the Lenders; and

            (c)   This Amendment has been executed by Borrower, Agent and the
Required Lenders, and counterparts hereof as so executed shall have been
delivered to Agent.

            5.    Representations and Warranties . Borrower hereby represents
and warrants to Agent and the Lenders that (a) Borrower has the legal power and
authority to execute and deliver this Amendment; (b) the officials executing
this Amendment have been duly authorized to execute and deliver the same and
bind Borrower with respect to the provisions hereof; (c) the execution and
delivery hereof by Borrower and the performance and observance by Borrower of
the provisions hereof do not violate or conflict with the organizational
agreements of Borrower or any law applicable to Borrower or result in a breach
of any provision of or constitute a default under any other agreement,
instrument or document binding upon or enforceable against Borrower; (d) no
Default or Event of Default exists under the Credit Agreement, nor will any

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occur immediately after the execution and delivery of this Amendment or by the
performance or observance of any provision hereof; (e) neither Borrower nor any
Subsidiary has any claim or offset against, or defense or counterclaim to, any
of Borrower’s or any Subsidiary’s obligations or liabilities under the Credit
Agreement or any Related Writing; and (f) this Amendment constitutes a valid and
binding obligation of Borrower in every respect, enforceable in accordance with
its terms.

            6.    Credit Agreement Unaffected . Each reference that is made in
the Credit Agreement or any other writing to the Credit Agreement shall
hereafter be construed as a reference to the Credit Agreement as amended hereby.
Except as herein otherwise specifically provided, all provisions of the Credit
Agreement shall remain in full force and effect and be unaffected hereby.

            7.    Waiver . Borrower and each Subsidiary, by signing below,
hereby waives and releases Agent and each of the Lenders and their respective
directors, officers, employees, attorneys, affiliates and subsidiaries from any
and all claims, offsets, defenses and counterclaims of which Borrower and any
Subsidiary is aware, such waiver and release being with full knowledge and
understanding of the circumstances and effect thereof and after having consulted
legal counsel with respect thereto.

            8.    Counterparts This Amendment may be executed in any number of
counterparts, by different parties hereto in separate counterparts and by
facsimile signature, each of which when so executed and delivered shall be
deemed to be an original and all of which taken together shall constitute but
one and the same agreement.

            9.    Governing Law . The rights and obligations of all parties
hereto shall be governed by the laws of the State of Ohio, without regard to
principles of conflicts of laws.

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            10.    JURY TRIAL WAIVER . BORROWER, AGENT, THE LENDERS AND EACH
GUARANTOR HEREBY WAIVE ANY RIGHT TO HAVE A JURY PARTICIPATE IN RESOLVING ANY
DISPUTE, WHETHER SOUNDING IN CONTRACT, TORT OR OTHERWISE, AMONG BORROWER, AGENT,
THE LENDERS, EACH GUARANTOR, OR ANY THEREOF, ARISING OUT OF, IN CONNECTION WITH,
RELATED TO, OR INCIDENTAL TO THE RELATIONSHIP ESTABLISHED AMONG THEM IN
CONNECTION WITH THIS AGREEMENT OR ANY NOTE OR OTHER INSTRUMENT, DOCUMENT OR
AGREEMENT EXECUTED OR DELIVERED IN CONNECTION HEREWITH OR THE TRANSACTIONS
RELATED THERETO.

            IN WITNESS WHEREOF, this Amendment has been duly executed and
delivered as of the date first above written.

    STERIS CORPORATION

        By: /s/ Laurie Brlas                                                  
Name: Laurie Brlas                                               Title: Senior
Vice President and Chief Financial
Officer                                                                 

    KEYBANK NATIONAL ASSOCIATION , as Agent and as a Lender

        By: /s/ J.T. Taylor                                                     
Name: J.T. Taylor                                                  Title: Vice
President                                      

    LASALLE BANK NATIONAL ASSOCIATION

        By: /s/ Robert M.Walker                                           Name:
Robert M.Walker                                       Title: Associate Vice
President                      

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    HARRIS TRUST AND SAVINGS BANK

        By: /s/ Sarah U. Johnston                                          Name:
Sarah U. Johnston                                      Title: Vice
President                                       

    NATIONAL CITY BANK

        By: /s/ Robert S. Coleman                                         Name:
Robert S. Coleman                                    Title: Vice
President                                      

    THE BANK OF NEW YORK

        By: /s/ Christopher T. Kordes                                   Name:
Christopher T. Kordes                               Title: Vice
President                                       

    PNC BANK, NATIONAL ASSOCIATION

        By: /s/ Joseph G. Moran                                            Name:
Joseph G. Moran                                        Title: Vice
President                                       

    BANK ONE, NA

        By: /s/ Glenn A. Currin                                            
Name: Glenn A. Currin                                         Title: Managing
Director                               

    U.S. BANK NATIONAL ASSOCIATION

        By: /s/ Derek Roudebush                                          Name:
Derek Roudebush                                      Title: Vice
President                                      

    FLEET NATIONAL BANK

        By: /s/ Edward McKenney                                        Name:
Edward McKenney                                    Title: Senior Vice
President                           

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    FIRSTMERIT BANK, N.A.

        By: /s/ Jonathan M. Isaacs                                         Name:
Jonathan M. Isaacs                                    Title: Vice
President                                      

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GUARANTOR ACKNOWLEDGMENT AND AGREEMENT

            Each of the undersigned (collectively, the “ Guarantors ” and,
individually, each a “ Guarantor ”) consents and agrees to and acknowledges the
terms of the foregoing Amendment No. 1 to Credit Agreement, dated as of July 25,
2002 (the “ Amendment ”). Each Guarantor specifically acknowledges the terms of
and consents to the waivers set forth in the Amendment. Each Guarantor further
agrees that its obligations pursuant to the Guaranty of Payment that it executed
in connection with the Credit Agreement shall remain in full force and effect
and be unaffected hereby.

            Each Guarantor, by signing below, hereby waives and releases Agent
and each of the Lenders and their respective directors, officers, employees,
attorneys, affiliates, and subsidiaries from any and all claims, offsets,
defenses, and counterclaims of which any of the Guarantors are aware, such
waiver and release being with full knowledge and understanding of the
circumstances and effect thereof and after having consulted legal counsel with
respect thereto.

            EACH GUARANTOR HEREBY WAIVES ANY RIGHT TO HAVE A JURY PARTICIPATE IN
RESOLVING ANY DISPUTE, WHETHER SOUNDING IN CONTRACT, TORT OR OTHERWISE, AMONG
BORROWER, AGENT, THE LENDERS, THE GUARANTORS, OR ANY THEREOF, ARISING OUT OF, IN
CONNECTION WITH, RELATED TO, OR INCIDENTAL TO THE RELATIONSHIP ESTABLISHED AMONG
THEM IN CONNECTION WITH THIS AGREEMENT OR ANY NOTE OR OTHER INSTRUMENT, DOCUMENT
OR AGREEMENT EXECUTED OR DELIVERED IN CONNECTION HEREWITH OR THE TRANSACTIONS
RELATED THERETO.

            IN WITNESS WHEREOF, this Guarantor Acknowledgment and Agreement has
been duly executed and delivered as of the date of the Amendment.

    MEDICAL & ENVIRONMENTAL DESIGNS, INC.
ECOMED, INC.
AMERICAN STERILIZER COMPANY
STERIS EUROPE, INC.
STERIS ASIA PACIFIC, INC.
STERIS INC.
HTD HOLDING CORP.
HSTD LLC
HAUSTED, INC.
ISOMEDIX INC.
ISOMEDIX OPERATIONS INC.

        By: /s/ Laurie Brlas                                                    
    Name: Laurie Brlas                                                    
Title: Senior Vice President and Chief Financial
Officer                                                                        
of, and on behalf of, each of the above Guarantors

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