SECURITIES & EXCHANGE COMMISSION
                             Washington, D.C. 20549
                             ----------------------

                                  SCHEDULE 13G*
                                 (Rule 13d-102)

             INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT
           TO RULES 13d-1(b), (c) AND (d) AND AMENDMENTS THERETO FILED
                              PURSUANT TO 13d-2(b)

                               STERIS Corporation
                                (Name of Issuer)

                                  Common Stock
                         (Title of Class of Securities)

                                    859152100
                                 (CUSIP Number)

                                 April 12, 2006
             (Date of event which requires filing of this statement)


     Check the appropriate box to designate the rule pursuant to which this
 Schedule 13G is filed:
     [ ]  Rule 13d-1(b)
     [x]  Rule 13d-1(c)
     [ ]  Rule 13d-1(d)





                               (Page 1 of 8 Pages)
- ----------------
     *The remainder of this cover page shall be filled out for a reporting
person's initial filing on this form with respect to the subject class of
securities, and for any subsequent amendment containing information which would
alter the disclosures provided in a prior cover page.

     The information required in the remainder of this cover page shall not be
deemed to be "filed" for purposes of Section 18 of the Securities Exchange Act
of 1934 ("Act") or otherwise subject to the liabilities of that section of the
Act but shall be subject to all other provisions of the Act (however, see the
Notes).





CUSIP No. 859152100                 13G                    Page 2 of 8 Pages

- -----------------------------------------------------------------------------
     (1)    NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NO.
            OF ABOVE PERSONS (ENTITIES ONLY)
                                                        Eminence Capital, LLC
- -----------------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP **
                                                                     (a) [ ]
                                                                     (b) [ ]
- -----------------------------------------------------------------------------
     (3)    SEC USE ONLY
- -----------------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION
                            New York
- -----------------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                                                -0-
SHARES         ______________________________________________________________

BENEFICIALLY   (6)  SHARED VOTING POWER
                                                3,450,000
OWNED BY       ______________________________________________________________

EACH           (7)  SOLE DISPOSITIVE POWER
                                                -0-
REPORTING      ______________________________________________________________

PERSON WITH    (8)  SHARED DISPOSITIVE POWER
                                                3,450,000
- -----------------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
                                                3,450,000
- -----------------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT
            IN ROW (9) EXCLUDES CERTAIN SHARES **                        [ ]
- -----------------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED
            BY AMOUNT IN ROW (9)
                                                5.1%
- -----------------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON **
                                                IA
- -----------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT!





CUSIP No. 859152100                 13G                    Page 3 of 8 Pages

- ----------------------------------------------------------------------------
     (1)    NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NO.
            OF ABOVE PERSONS (ENTITIES ONLY)
                                                             Eminence GP, LLC
- -----------------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP **
                                                                     (a) [ ]
                                                                     (b) [ ]
- -----------------------------------------------------------------------------
     (3)    SEC USE ONLY
- -----------------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION
                            New York
- -----------------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                                                -0-
SHARES         ______________________________________________________________

BENEFICIALLY   (6)  SHARED VOTING POWER
                                                2,137,640
OWNED BY       ______________________________________________________________

EACH           (7)  SOLE DISPOSITIVE POWER
                                                -0-
REPORTING      ______________________________________________________________

PERSON WITH    (8)  SHARED DISPOSITIVE POWER
                                                2,137,640
- -----------------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
                                                2,137,640
- -----------------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT
            IN ROW (9) EXCLUDES CERTAIN SHARES **                        [ ]
- -----------------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED
            BY AMOUNT IN ROW (9)
                                                3.2%
- -----------------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON **
                                                OO
- -----------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT!





CUSIP No. 859152100                 13G                    Page 4 of 8 Pages

- ----------------------------------------------------------------------------
     (1)    NAMES OF REPORTING PERSONS
            I.R.S. IDENTIFICATION NO.
            OF ABOVE PERSONS (ENTITIES ONLY)
                                                             Ricky C. Sandler
- -----------------------------------------------------------------------------
     (2)    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP **
                                                                     (a) [ ]
                                                                     (b) [ ]
- -----------------------------------------------------------------------------
     (3)    SEC USE ONLY
- -----------------------------------------------------------------------------
     (4)    CITIZENSHIP OR PLACE OF ORGANIZATION
                            United States
- -----------------------------------------------------------------------------
NUMBER OF      (5)  SOLE VOTING POWER
                                                -0-
SHARES         ______________________________________________________________

BENEFICIALLY   (6)  SHARED VOTING POWER
                                                3,450,000
OWNED BY       ______________________________________________________________

EACH           (7)  SOLE DISPOSITIVE POWER
                                                -0-
REPORTING      ______________________________________________________________

PERSON WITH    (8)  SHARED DISPOSITIVE POWER
                                                3,450,000
- -----------------------------------------------------------------------------
     (9)    AGGREGATE AMOUNT BENEFICIALLY OWNED
            BY EACH REPORTING PERSON
                                                3,450,000
- -----------------------------------------------------------------------------
     (10)   CHECK BOX IF THE AGGREGATE AMOUNT
            IN ROW (9) EXCLUDES CERTAIN SHARES **                        [ ]
- -----------------------------------------------------------------------------
     (11)   PERCENT OF CLASS REPRESENTED
            BY AMOUNT IN ROW (9)
                                                5.1%
- -----------------------------------------------------------------------------
     (12)   TYPE OF REPORTING PERSON **
                                                IN
- -----------------------------------------------------------------------------
                     ** SEE INSTRUCTIONS BEFORE FILLING OUT!





CUSIP No. 859152100                 13G                    Page 5 of 8 Pages

Item 1(a).     Name of Issuer:

     The name of the issuer is STERIS Corporation (the "Company").

Item 1(b).     Address of Issuer's Principal Executive Offices:

     The Company's principal executive offices are located at 5960 Heisley Road,
Mentor, Ohio 44060-1834

Item 2(a).     Name of Person Filing:

This statement is filed on behalf of each of the following persons
(collectively, the "Reporting Persons"):

(i) Eminence Capital, LLC, a New York limited liability company ("Eminence
Capital");

(ii) Eminence GP, LLC, a New York limited liability company ("Eminence GP"); and

(iii) Ricky C. Sandler, a U.S. Citizen ("Mr. Sandler").


This statement relates to Shares of Common Stock as defined in items 2(d) and
2(e) below held for the accounts of: Eminence Partners, LP, a New York limited
partnership ("Eminence I"); Eminence Partners II, LP, a New York limited
partnership ("Eminence II"); Eminence Long Alpha, LP, a Delaware limited
partnership ("ELA") and Eminence Leveraged Long Alpha, LP, a Delaware limited
partnership ("ELLA" and together with Eminence I, Eminence II, and ELA, the
"Partnerships"); as well as Eminence Long Alpha Master Fund, Ltd. and Eminence
Leveraged Long Alpha Master Fund, Ltd. (the "Offshore Master Funds") and
Eminence Fund, Ltd. ("Eminence Offshore"), each a Cayman Islands company, and
collectively referred to as the "Offshore Funds").

Eminence Capital serves as the investment manager to the Partnerships with
respect to the shares of Common Stock directly owned by the Partnerships and the
Offshore Funds and may be deemed to have voting and dispositive power over the
Shares held for the accounts of the Partnerships and the Offshore Funds.

Eminence GP serves as general partner or manager with respect to the shares of
Common Stock directly owned by the Partnerships and the Offshore Master Funds,
respectively, and may be deemed to have voting and dispositive power over the
Shares held for the accounts of the Partnerships and the Offshore Master Funds.

Ricky C. Sandler, with respect to the shares of Common Stock directly owned by
the Partnerships and the Offshore Funds over which Mr. Sandler has investment
discretion in his role as Managing Member of each Eminence Capital and Eminence
GP.





CUSIP No. 859152100                 13G                   Page 6 of 8 Pages

Item 2(b).     Address of Principal Business Office or, if None, Residence:

     The address of the principal business and principal office of the
Partnerships, Eminence GP and the Investment Manager is 65 East 55th Street,
25th Floor, New York, NY 10022. The business address of Mr. Sandler is 65 East
55th Street, 25th Floor, New York, NY 10022.

Item 2(c).     Citizenship:

       (i) Eminence Capital, a New York limited liability company;

      (ii) Eminence GP, a New York limited liability company; and

     (iii) Mr. Sandler, a United States Citizen.


Item 2(d).     Title of Class of Securities:
     Common stock(the "Common Stock").

Item 2(e).  CUSIP Number:  859152100

Item 3. If this statement is filed pursuant to Rules 13d-1(b) or 13d-2(b) or
(c), check whether the person filing is a:

          (a) [ ]  Broker or dealer registered under Section 15 of the
                   Act,

          (b) [ ]  Bank as defined in Section 3(a)(6) of the Act,

          (c) [ ]  Insurance Company as defined in Section 3(a)(19) of
                   the Act,

          (d) [ ]  Investment Company registered under Section 8 of the
                   Investment Company Act of 1940,

          (e) [ ]  Investment Adviser in accordance with Rule
                   13d-1 (b)(1)(ii)(E),

          (f) [ ]  Employee Benefit Plan or Endowment Fund in accordance
                   with Rule 13d-1 (b)(1)(ii)(F),

          (g) [ ]  Parent Holding Company or control person in accordance
                   with Rule 13d-1 (b)(1)(ii)(G),

          (h) [ ]  Savings Association as defined in Section 3(b) of the
                   Federal Deposit Insurance Act,

          (i) [ ]  Church Plan that is excluded from the definition of an
                   investment company under Section 3(c)(14) of the
                   Investment Company Act of 1940,

          (j) [ ]  Group, in accordance with Rule 13d-1(b)(1)(ii)(J).

     Not applicable





CUSIP No. 859152100                 13G                  Page 7 of 8 Pages

Item 4.   Ownership.

      A. Eminence Capital, LLC
            (a) Amount beneficially owned: 3,450,000
            (b) Percent of class: 5.1%. The percentages used herein and in the
rest of Item 4 are calculated based upon the 67,657,958 shares of Common Stock
outstanding at January 31,2006, as set forth in the Company's Form 10-Q for the
quarterly period ended December 31, 2005.
            (c)(i) Sole power to vote or direct the vote: 0
              (ii) Shared power to vote or direct the vote: 3,450,000
             (iii) Sole power to dispose or direct the disposition: 0
              (iv) Shared power to dispose or direct the disposition: 3,450,000


      B. Eminence GP, LLC
            (a) Amount beneficially owned: 2,137,640
            (b) Percent of class: 3.2%
            (c)(i) Sole power to vote or direct the vote: 0
              (ii) Shared power to vote or direct the vote: 2,137,640
             (iii) Sole power to dispose or direct the disposition: 0
              (iv) Shared power to dispose or direct the disposition: 2,137,640


      C. Ricky C. Sandler
            (a) Amount beneficially owned: 3,450,000
            (b) Percent of class: 5.1%
            (c)(i) Sole power to vote or direct the vote: 0
              (ii) Shared power to vote or direct the vote: 3,450,000
             (iii) Sole power to dispose or direct the disposition: 0
              (iv) Shared power to dispose or direct the disposition: 3,450,000

Item 5.     Ownership of Five Percent or Less of a Class.

     Not Applicable.


Item 6.     Ownership of More than Five Percent on Behalf of Another Person.

     Eminence GP, the general partner of the Partnerships and the manager of the
Offshore Funds, has the power to direct the affairs of the Partnerships and the
Offshore Funds, including decisions respecting the disposition of the proceeds
from the sale of the shares. The Investment Manager provides investment
management services to the Partnerships and the Offshore Funds, and has the
power to direct the investment activities of the Partnerships and the Offshore
Funds, including the power to make decisions with respect to the disposition of
the proceeds from the sale of the shares. Mr. Sandler serves as the Managing
Member of Eminence GP and the Investment Manager and in that capacity directs
their operations.

Item 7.     Identification and Classification of the Subsidiary Which Acquired
the Security Being Reported on by the Parent Holding Company.

     Not Applicable.





CUSIP No. 859152100                 13G                  Page 8 of 8 Pages


Item 8.    Identification and Classification of Members of the Group.

     Not Applicable.

Item 9.    Notice of Dissolution of Group.

     Not Applicable.

Item 10.   Certification.

     Each of the Reporting Persons hereby makes the following certification:

          By signing below I certify that, to the best of my knowledge and
belief, the securities referred to above were not acquired and are not held for
the purpose of or with the effect of changing or influencing the control of the
issuer of the securities and were not acquired and are not held in connection
with or as a participant in any transaction having that purpose or effect.

SIGNATURES

After reasonable inquiry and to the best of our knowledge and belief, the
undersigned certify that the information set forth in this statement is true,
complete and correct.


DATED:  April 24, 2006

                                    /s/ Ricky C. Sandler
                                    ---------------------
                                    Ricky C. Sandler, individually, and as
                                    Managing Member of
                                    Eminence Capital, LLC,
                                       and as
                                    Managing Member of
                                    Eminence GP, LLC

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