United States Securities and Exchange Commission

Washington, D. C. 20549

 ___________________________________________________________________

FORM 10-K/A

Amendment No. 1

x Annual Report Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

For the fiscal year ended March 31, 2012

OR

o Transition Report Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

For the transition period from                      to                     

Commission file number 1-14643

STERIS Corporation

(Exact name of registrant as specified in its charter)

Ohio		34-1482024
(State or other jurisdiction of incorporation or organization)		(IRS Employer Identification No.)
5960 Heisley Road, Mentor, Ohio (Address of principal executive offices)	44060-1834 (Zip Code)	440-354-2600 (Registrant’s telephone number including area code)

SECURITIES REGISTERED PURSUANT TO SECTION 12(B) OF THE ACT:

Title of each class	Name of Exchange on Which Registered
Common Shares, without par value	New York Stock Exchange

SECURITIES REGISTERED PURSUANT TO SECTION 12(G) OF THE ACT:

None

Indicate by check mark if the Registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes  x    No   o

Indicate by check mark if the Registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes  o    No   x

Indicate by check mark whether the Registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the Registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes  x    No   o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 229.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes  x    No   o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of the Registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.  o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer,” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Large Accelerated Filer  x	Accelerated Filer  o
Non-Accelerated Filer  o (Do not check if a smaller reporting company)	Smaller Reporting Company  o

Indicate by check mark whether the Registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes  o    No   x

The aggregate market value of the voting stock held by non-affiliates of the Registrant, computed by reference to the closing price of such stock as of September 30, 2011: $1,539,707,782

The number of Common Shares outstanding as of May 18, 2012: 57,805,687

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Proxy Statement for the 2012 Annual Meeting – Part III

EXPLANATORY NOTE

The STERIS Corporation (the “Company” “we” and “us”) is filing this Amendment No. 1 on Form 10-K/A in order to amend the Company’s Annual Report on Form 10-K for the fiscal year ended March 31, 2012 filed with the Securities and Exchange Commission (“SEC”) on May 29, 2012 for the sole purpose of filing the Interactive Data File as Exhibit 101. The attached Exhibit 101 was omitted from our original 10-K filing.

No other changes have been made to the Form 10-K. This Form 10-K/A continues to speak as of the original filing date of the Form 10-K, does not reflect events that may have occurred subsequent to the original filing date, and does not modify or update any related disclosures made in the Form 10-K.

ITEM 15. EXHIBITS AND FINANCIAL STATEMENT SCHEDULE

LIST OF CONSOLIDATED FINANCIAL STATEMENTS AND FINANCIAL STATEMENT SCHEDULE

(a) (1) The following consolidated financial statements of STERIS Corporation and subsidiaries are included in Item 8:

Consolidated Balance Sheets – March 31, 2012 and 2011.

Consolidated Statements of Income – Years ended March 31, 2012, 2011, and 2010.

Consolidated Statements of Cash Flows – Years ended March 31, 2012, 2011, and 2010.

Consolidated Statements of Shareholders’ Equity – Years ended March 31, 2012, 2011, and 2010.

Notes to Consolidated Financial Statements.

(a) (2) The following consolidated financial statement schedule of STERIS Corporation and subsidiaries is included in Item 8:

Schedule II - Valuation and Qualifying Accounts

All other schedules for which provision is made in the applicable accounting regulation of the SEC are not required under the related instructions or are inapplicable and, therefore, have been omitted.

(a) (3) All exhibits as set forth on the Exhibit Index, which is incorporated herein by reference.

SIGNATURES

Pursuant to the requirements of Sections 13 or 15(d) of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized, on the date indicated.

		STERIS CORPORATION (Registrant)
Date:	May 30, 2012	By:	/S/    MICHAEL J. TOKICH
		Michael J. Tokich
		Senior Vice President and Chief Financial Officer

EXHIBIT INDEX

(a)

Exhibit Number	Exhibit Description
3.1	1992 Amended Articles of Incorporation of STERIS Corporation, as amended on May 14, 1996, November 6, 1996, and August 6, 1998 (filed as Exhibit 3.1 to Form 10-K for the fiscal year ended March 31, 2000 (Commission File No. 1-14643), and incorporated herein by reference).
3.2	Amended and Restated Regulations of STERIS Corporation, as amended on July 26, 2007 (filed as Exhibit 3.2 to Form 10-Q for the fiscal quarter ended June 30, 2007 (Commission File No. 1-14643), and incorporated herein by reference).
4.1	Specimen Form of Common Stock Certificate (filed as Exhibit 4.1 to Form 10-K for the fiscal year ended March 31, 2002 (Commission File No. 1-14643), and incorporated herein by reference).
10.1	Amended and Restated Non-Qualified Stock Option Plan (filed as Exhibit 10.1 to Form 10-K for the fiscal year ended March 31, 2005 (Commission File No. 1-14643), and incorporated herein by reference).
10.2	STERIS Corporation 1994 Equity Compensation Plan (filed as Exhibit 10.2 to Form 10-K for the fiscal year ended March 31, 2005 (Commission File No. 1-14643), and incorporated herein by reference).
10.3	STERIS Corporation 1994 Nonemployee Directors Equity Compensation Plan (filed as Exhibit 10.3 to Form 10-K for the fiscal year ended March 31, 2002 (Commission File No. 1-14643), and incorporated herein by reference).
10.4	STERIS Corporation Form of Nonqualified Stock Option Grant Agreement for Directors (filed as Exhibit 10.4 to Form 10-Q for the fiscal quarter ended December 31, 2004 (Commission File No. 1-14643), and incorporated herein by reference).
10.5	STERIS Corporation Form of Nonqualified Stock Option Agreement for Employees (filed as Exhibit 10.2 to Form 10-Q for the fiscal quarter ended December 31, 2004 (Commission File No. 1-14643), and incorporated herein by reference).
10.6	STERIS Corporation 1997 Stock Option Plan (filed as Exhibit 10.5 to Form 10-K for the fiscal year ended March 31, 2003 (Commission File No. 1-14643), and incorporated herein by reference).
10.7	STERIS Corporation 1998 Long-Term Incentive Stock Plan (filed as Exhibit 10.8 to Form 10-K for fiscal year ended March 31, 1999 (Commission File No. 1-14643), and incorporated herein by reference).
10.8	STERIS Corporation 2002 Stock Option Plan (filed as Exhibit 10.7 to Form 10-K for the fiscal year ended March 31, 2003 (Commission File No. 1-14643), and incorporated herein by reference).
10.9	STERIS Corporation 2006 Long-Term Equity Incentive Plan (filed as Exhibit 10.1 to Form 8-K filed July 28, 2006 (Commission File No. 1-14643), and incorporated herein by reference).
10.10	Amendment No. 1 to STERIS Corporation 2006 Long-Term Equity Incentive Plan (filed as Exhibit 10.11 to Form 10-K for the fiscal year ended March 31, 2007 (Commission File No. 1-14643), and incorporated herein by reference).
10.11	STERIS Corporation Form of Restricted Stock Agreement for Employees (filed as Exhibit 10.3 to Form 8-K filed July 28, 2006 (Commission File No. 1-14643), and incorporated herein by reference).
10.12	STERIS Corporation Form of Restricted Stock Agreement for Directors (filed as Exhibit 10.5 to Form 8-K filed July 28, 2006 (Commission File No. 1-14643), and incorporated herein by reference).
10.13	STERIS Corporation Form of Restricted Stock Unit Agreement for Employees (filed as Exhibit 10.5 to Form 10-Q for the fiscal quarter ended September 30, 2007 (Commission File No. 1-14643), and incorporated herein by reference).
10.14	STERIS Corporation Form of Nonqualified Stock Option Agreement for Employees (filed as Exhibit 10.7 to Form 10-Q for the fiscal quarter ended September 30, 2006 (Commission File No. 1-14643), and incorporated herein by reference).

10.15	STERIS Corporation Form of Nonqualified Stock Option Agreement for Nonemployee Directors (filed as Exhibit 10.8 to Form 10-Q for the fiscal quarter ended September 30, 2006 (Commission File No. 1-14643), and incorporated herein by reference).
10.16	STERIS Corporation Form of Restricted Stock Agreement for Employees (filed as Exhibit 10.1 to Form 10-Q for the fiscal quarter ended June 30, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.17	STERIS Corporation Form of Restricted Stock Agreement for Nonemployee Directors (filed as Exhibit 10.2 to Form 10-Q for the fiscal quarter ended June 30, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.18	STERIS Corporation Form of Nonqualified Stock Option Agreement for Employees (filed as Exhibit 10.3 to Form 10-Q for the fiscal quarter ended June 30, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.19	STERIS Corporation Form of Nonqualified Stock Option Agreement for Nonemployee Directors (filed as Exhibit 10.4 to Form 10-Q for the fiscal quarter ended June 30, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.20	STERIS Corporation Form of Restricted Stock Agreement for Employees (filed as Exhibit 10.1 to Form 10-Q for the fiscal quarter ended June 30, 2009 (Commission File No. 1-14643), and incorporated herein by reference).
10.21	STERIS Corporation Form of Non-Qualified Stock Option Agreement for Employees (filed as Exhibit 10.2 to Form 10-Q for the fiscal quarter ended June 30, 2009 (Commission File No. 1-14643), and incorporated herein by reference).
10.22	STERIS Corporation 2006 Long-Term Equity Incentive Plan (as Amended and Restated Effective July 28, 2011) (filed as Exhibit A to Schedule 14A (Definitive Proxy Statement) filed June 7, 2011 (Commission File No. 1-14643), and incorporated herein by reference).
10.23	STERIS Corporation Form of Non-Qualified Stock Option Agreement for Employees. (filed as Exhibit 10.22 to Form 10-K for the fiscal year ended March 31, 2011(Commission File No. 1-14643), and incorporated herein by reference).
10.24	STERIS Corporation Form of Restricted Stock Agreement for Employees (filed as Exhibit 10.23 to Form 10-K for the fiscal year ended March 31, 2011(Commission File No. 1-14643), and incorporated herein by reference).
10.25	STERIS Corporation Form of Restricted Stock Agreement for Employees (filed as Exhibit 10.1 to Form 10-Q for the fiscal quarter ended June 30, 2011 (Commission File No. 1-14643), and incorporated herein by reference.
10.26	STERIS Corporation Form of Nonqualified Stock Option Agreement for Employees (filed as Exhibit 10.2 to Form 10-Q for the fiscal quarter ended June 30, 2011 (Commission File No. 1-14643), and incorporated herein by reference).
10.27*	STERIS Corporation Form of Restricted Stock Agreement for Employees.
10.28*	STERIS Corporation Form of Restricted Stock Agreement for Employees.
10.29	STERIS Corporation Deferred Compensation Plan Document (filed as Exhibit 10.1 to Form 8-K filed September 1, 2006 (Commission File No. 1-14643), and incorporated herein by reference).
10.30	STERIS Corporation Deferred Compensation Plan Document (as Amended and Restated Effective January 1, 2009) (filed as Exhibit 10.1 to Form 10-Q for the fiscal quarter ended December 31, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.31	Amended and Restated Adoption Agreement related to STERIS Corporation Deferred Compensation Plan (filed as Exhibit 10.2 to Form 10-Q filed for the fiscal quarter ended December 31, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.32	Amendment No. 1 to STERIS Corporation Deferred Compensation Plan Document (as Amended and Restated Effective January 1, 2009) dated November 4, 2011 (filed as Exhibit 10.1 to Form 10-Q for the fiscal quarter ended December 31, 2011 (Commission File No. 1-14643), and incorporated herein by reference).

10.33	STERIS Corporation Incentive Compensation Plan (filed as Exhibit 10.1 to Form 8-K filed May 7, 2009 (Commission File No. 1-14643), and incorporated herein by reference).
10.34	STERIS Corporation Senior Executive Management Incentive Compensation Plan, as Amended and Restated Effective April 1, 2010 (filed as Appendix A to Schedule 14A (Definitive Proxy Statement) filed June 8, 2010 (Commission File No. 1-14643), and incorporated herein by reference).
10.35	Form of Change of Control Agreement between STERIS Corporation and certain executive officers of STERIS Corporation other than Mr. Walter M Rosebrough, Jr. (filed as Exhibit 10.2 to Form 10-Q for the fiscal quarter ended June 30, 1999 (Commission File No. 1-14643), and incorporated herein by reference).
10.36	Employment Agreement dated September 7, 2007 between STERIS Corporation and Mr. Rosebrough (filed as Exhibit 10.3 to Form 10-Q for the fiscal quarter ended September 30, 2007 (Commission File No. 1-14643), and incorporated herein by reference).
10.37	Agreement dated September 7, 2007 between STERIS Corporation and Mr. Rosebrough (filed as Exhibit 10.4 to Form 10-Q for the fiscal quarter ended September 30, 2007 (Commission File No. 1-14643), and incorporated herein by reference).
10.38	Executive Retention Agreement dated April 1, 2010 between STERIS Corporation and Dr. Peter Burke (filed as Exhibit 10.1 to Form10-Q for the fiscal quarter ended June 30, 2010 (Commission File No. 1-14643), and incorporated herein by reference).
10.39	Form of Indemnification Agreement between STERIS Corporation and each of its directors and executive officers (filed as Exhibit 10.31 to Form 10-K for the fiscal year ended March 31, 2010 (Commission File No. 1-14643), and incorporated herein by reference).
10.40	Agreement dated as of April 23, 2008 by and among STERIS Corporation, Richard C. Breeden, Robert H. Fields, and the Breeden Investors identified therein (filed as Exhibit 10.1 to Form 8-K filed April 24, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.41	Agreement dated November 4, 2011 between STERIS Corporation and Bank of America, N.A. providing Transfer and Advised Line for Letters of Credit (filed as Exhibit 10.2 to Form 10-Q for the fiscal quarter ended December 31, 2011 (Commission File No. 1-14643), and incorporated herein by reference).
10.42	Form of Note Purchase Agreements, dated December 17, 2003, between STERIS Corporation and certain institutional investors (filed as Exhibit 10.3 to Form 10-Q for the fiscal quarter ended December 31, 2003 (Commission File No. 1-14643), and incorporated herein by reference).
10.43	First Amendment dated as of August 15, 2008 to Note Purchase Agreements dated as of December 17, 2003 between STERIS Corporation and certain institutional investors (filed as Exhibit 10.1 to Form 10-Q for the fiscal quarter ended September 30, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.44	Subsidiary Guaranty dated December 17, 2003, by certain subsidiaries of STERIS Corporation (filed as Exhibit 10.4 to Form 10-Q for the fiscal quarter ended December 31, 2003 (Commission File No. 1-14643), and incorporated herein by reference).
10.45	Guaranty Supplement dated January 7, 2005, by STERIS Isomedix Services, Inc. and STERIS Corporation (filed as Exhibit 10.20 to Form 10-K for the fiscal year ended March 31, 2005 (Commission File No. 1-14643), and incorporated herein by reference).
10.46	Guaranty Supplement dated July 11, 2011 by STERIS Brazil Holdings, LLC and STERIS Corporation [For 2003 Senior Notes] (filed as Exhibit 10.1 to Form 10-Q for the fiscal quarter ended September 30, 2011 (Commission File No. 1-14643), and incorporated herein by reference).
10.47	Guaranty Supplement dated December 7, 2010 by PeriOptimum, Inc. and STERIS Corporation (filed as Exhibit 10.42 to Form 10-K for the fiscal year ended March 31, 2011 (Commission File No. 1-14643), and incorporated herein by reference).
10.48	Form of Note Purchase Agreements dated as of August 15, 2008, between STERIS Corporation and certain institutional investors (filed as Exhibit 10.2 to Form 10-Q for the fiscal quarter ended September 30, 2008 (Commission File No. 1-14643), and incorporated herein by reference).

10.49	Subsidiary Guaranty dated as of August 15, 2008, by certain subsidiaries of STERIS Corporation (filed as Exhibit 10.3 to Form 10-Q for the fiscal quarter ended September 30, 2008 (Commission File No. 1-14643), and incorporated herein by reference).
10.50	Guaranty Supplement dated July 11, 2011 by STERIS Brazil Holdings, LLC and STERIS Corporation [For 2008 Senior Notes] (filed as Exhibit 10.2 to Form 10-Q for the fiscal quarter ended September 30, 2011 (Commission File No. 1-14643), and incorporated herein by reference).
10.51	Guaranty Supplement dated December 7, 2010 by PeriOptimum, Inc. and STERIS Corporation (filed as Exhibit 10.45 to Form 10-K for the fiscal year ended March 31, 2011 (Commission File No. 1-14643), and incorporated herein by reference).
21.1*	Subsidiaries of STERIS Corporation.
23.1*	Consent of Independent Registered Public Accounting Firm.
24.1*	Power of Attorney.
31.1*	Certification of the Principal Executive Officer Pursuant to Exchange Act Rule 13a-14(a)/15d-14(a).
31.2*	Certification of the Principal Financial Officer Pursuant to Exchange Act Rule 13a-14(a)/15d-14(a).
32.1*	Certification of the Principal Executive Officer and the Principal Financial Officer Pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.
EX-101	Instance Document.
EX-101	Schema Document.
EX-101	Calculation Linkbase Document.
EX-101	Definition Linkbase Document.
EX-101	Labels Linkbase Document.
EX-101	Presentation Linkbase Document.

* Previously filed with the Company's Form 10-K for the fiscal year ended March 31, 2012.