SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D
                                (Amendment No. 4)

                   Under the Securities Exchange Act of 1934*

                         Flow International Corporation
--------------------------------------------------------------------------------
                                (Name of Issuer)

                     Common Stock, par value $0.01 per share
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    343468104
--------------------------------------------------------------------------------
                      (CUSIP Number of Class of Securities)

                                 Daniel S. Loeb
                                 Third Point LLC
                                 390 Park Avenue
                               New York, NY 10022
                                 (212) 224-7400
--------------------------------------------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                   Copies to:
                            Michael A. Schwartz, Esq.
                          Willkie Farr & Gallagher LLP
                               787 Seventh Avenue
                             New York, NY 10019-6099
                                 (212) 728-8000

                                September 5, 2008
--------------------------------------------------------------------------------
                          (Date of Event which Requires
                            Filing of this Schedule)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of ss.ss. 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the
following box: [ ]

NOTE: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Rule 240.13d-7 for other
parties to whom copies are to be sent.

* 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
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose 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).





                                     SCHEDULE 13D

-------------------------------                              -------------------
CUSIP No. 343468104                                          Page 2 of 9 Pages
-------------------------------                              -------------------


----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Third Point LLC
----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP    (a) [ ]
                                                                (b) [X]
----------- --------------------------------------------------------------------
    3       SEC USE ONLY

----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)     [ ]
----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            Delaware
--------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
                         8      SHARED VOTING POWER
NUMBER OF SHARES
BENEFICIALLY OWNED              3,850,000
BY EACH REPORTING     --------- ------------------------------------------------
PERSON WITH              9      SOLE DISPOSITIVE POWER

                                0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                3,850,000
----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            3,850,000
----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES* [ ]
----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            9.98%
----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            OO
----------- --------------------------------------------------------------------







                                      SCHEDULE 13D

-------------------------------                              -------------------
CUSIP No. 343468104                                          Page 3 of 9 Pages
-------------------------------                              -------------------


----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Daniel S. Loeb
----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP    (a) [ ]
                                                                (b) [X]
----------- --------------------------------------------------------------------
    3       SEC USE ONLY

----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            AF
----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)     [ ]
----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            United States
--------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
                         8      SHARED VOTING POWER
NUMBER OF SHARES
BENEFICIALLY OWNED              3,850,000
BY EACH REPORTING     --------- ------------------------------------------------
PERSON WITH              9      SOLE DISPOSITIVE POWER

                                0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                3,850,000
----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            3,850,000
----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES* [ ]
----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            9.98%
----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            IN
----------- --------------------------------------------------------------------











                                      SCHEDULE 13D

-------------------------------                              -------------------
CUSIP No. 343468104                                          Page 4 of 9 Pages
-------------------------------                              -------------------


----------- --------------------------------------------------------------------
    1       NAME OF REPORTING PERSON
            I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

            Third Point Offshore Fund, Ltd.
----------- --------------------------------------------------------------------
    2       CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP    (a) [ ]
                                                                (b) [X]
----------- --------------------------------------------------------------------
    3       SEC USE ONLY

----------- --------------------------------------------------------------------
    4       SOURCE OF FUNDS*

            WC
----------- --------------------------------------------------------------------
    5       CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDING IS REQUIRED PURSUANT TO
            ITEMS 2(d) or 2(e)     [ ]
----------- --------------------------------------------------------------------
    6       CITIZENSHIP OR PLACE OF ORGANIZATION

            Cayman Islands
--------------------- --------- ------------------------------------------------
                         7      SOLE VOTING POWER

                                0
                      --------- ------------------------------------------------
                         8      SHARED VOTING POWER
NUMBER OF SHARES
BENEFICIALLY OWNED              2,532,100
BY EACH REPORTING     --------- ------------------------------------------------
PERSON WITH              9      SOLE DISPOSITIVE POWER

                                0
                      --------- ------------------------------------------------
                         10     SHARED DISPOSITIVE POWER

                                2,532,100
----------- --------------------------------------------------------------------
    11      AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH PERSON

            2,532,100
----------- --------------------------------------------------------------------
    12      CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
            SHARES* [ ]
----------- --------------------------------------------------------------------
    13      PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)

            6.6%
----------- --------------------------------------------------------------------
    14      TYPE OF REPORTING PERSON*

            OO
----------- --------------------------------------------------------------------







     This Amendment No. 4 amends the Schedule 13D filed on February 2, 2007 (as
amended by Amendment No. 1 thereto filed on April 4, 2007, Amendment No. 2
thereto filed on April 23, 2007, Amendment No. 3 thereto filed on April 9, 2008
and this Amendment No. 4, the "Schedule 13D") and is being filed on behalf of
Third Point LLC, a Delaware limited liability company (the "Management
Company"), Daniel S. Loeb, an individual, and Third Point Offshore Fund, Ltd., a
Cayman Islands limited liability exempted company (the "Offshore Fund", and
together with Mr. Loeb and the Management Company, the "Reporting Persons").
This Amendment No. 4 relates to the Common Stock, par value $0.01 per share, of
Flow International Corporation, a Washington corporation (the "Company"). The
Management Company is the investment manager or adviser to a variety of funds
and managed accounts (such funds and accounts, including the Offshore Fund, the
"Funds"). The Funds directly own the Common Stock to which the Schedule 13D
relates, and Mr. Loeb and the Management Company may be deemed to have
beneficial ownership over such Common Stock by virtue of the authority granted
to them by the Funds to vote and to dispose of the securities held by the Funds,
including the Common Stock.

Item 3.   Source and Amount of Funds or Other Consideration.

     Item 3 of the Schedule 13D is hereby amended and restated as follows:

     The Funds have expended an aggregate of approximately $20,932,404 of their
own investment capital to acquire the 3,850,000 shares of Common Stock held by
them. The Offshore Fund has expended an aggregate of approximately $13,382,207
of its own investment capital to acquire its 2,532,100 shares of Common Stock.
The Funds effect purchases of securities primarily through margin accounts
maintained for them with Goldman, Sachs & Co., Citigroup Global Markets, Inc.,
UBS Securities LLC, Morgan Stanley & Co. Incorporated and Bear, Stearns
Securities Corp., which may extend margin credit to the Funds as and when
required to open or carry positions in the margin accounts, subject to
applicable Federal margin regulations, stock exchange rules and the firms'
credit policies. In such instances, the positions held in the margin accounts
are pledged as collateral security for the repayment of debit balances in the
accounts.

Item 5.   Interest in Securities of the Issuer.

     Item 5 of the Schedule 13D is hereby amended and restated as follows:

     (a) As of the date hereof, the Management Company and Mr. Loeb beneficially
own 3,850,000 shares of Common Stock (the "Shares"). The Shares represent 9.98%
of the 38,594,083 shares of Common Stock outstanding as of August 22, 2008, as
reported in the Company's Quarterly Report on Form 10-Q for the quarterly period
ended July 31, 2008. The percentages used herein and in the rest of this
statement are calculated based upon this number of outstanding shares. The
Offshore Fund directly beneficially owns 2,532,100 shares of Common Stock,
representing 6.6% of the outstanding shares of Common Stock as of the date
hereof.

     (b) The Management Company and Mr. Loeb share voting and dispositive power
over the 3,850,000 shares of Common Stock held directly by the Funds. The
Management Company, Mr. Loeb and the Offshore Fund share voting power and
dispositive power over the 2,532,100 shares of Common Stock held by the Offshore
Fund.

                                       5


     (c) Schedule A hereto sets forth certain information with respect to
transactions by the Funds (at the direction of the Management Company and Mr.
Loeb) in Common Stock during the past 60 days. Schedule B hereto sets forth
certain information with respect to transactions during the past 60 days by the
Offshore Fund (at the direction of the Management Company and Mr. Loeb) in
Common Stock. All of the transactions set forth on Schedule A and Schedule B
were effected in the NASDAQ Global Market. Except as set forth on Schedules A
and B, during the past 60 days there were no transactions in the Common Stock
effected by the Reporting Persons, nor, to the best of their knowledge, any of
their directors, executive officers, general partners or members.

     (d) Other than the Funds which directly hold the Shares, and except as set
forth in this Item 5, no person is known to have the right to receive or the
power to direct the receipt of dividends from, or the proceeds from the sale of,
the Shares.

     (e) Not applicable.

Item 7.   Material to Be Filed as Exhibits.

99.7     Power of Attorney granted by Daniel S. Loeb in favor of James P.
         Gallagher, William Song, Joshua L. Targoff and Bruce Wilson,
         dated June 12, 2008.


                         [Signatures on following page]


                                       6








                                   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:  September 9, 2008

                                 THIRD POINT LLC

                                 By:  Daniel S. Loeb, Chief Executive Officer


                                 By:  /s/ William Song
                                      ------------------------------------------
                                      Name:   William Song
                                      Title:  Attorney-in-Fact



                                 THIRD POINT OFFSHORE FUND, LTD.

                                 By:    Daniel S. Loeb, Director


                                 By:  /s/ William Song
                                      ------------------------------------------
                                      Name:   William Song
                                      Title:  Attorney-in-Fact


                                 DANIEL S. LOEB


                                 By:  /s/ William Song
                                      ------------------------------------------
                                      Name:   William Song
                                      Title:  Attorney-in-Fact


               [SIGNATURE PAGE TO AMENDMENT NO. 4 TO SCHEDULE 13D
                 WITH RESPECT TO FLOW INTERNATIONAL CORPORATION]






                                                    Schedule A
                                                    ----------


                                   (Transactions by the Funds in Common Stock
                                             during the past 60 days)


         Date                   Transaction                       Shares                       Price Per Share($)
         ----                   -----------                       ------                       ------------------

------------------------ ---------------------------- --------------------------------- -----------------------------------
                                                                               
       7/31/2008                    SELL                        (321,000)                             6.660
------------------------ ---------------------------- --------------------------------- -----------------------------------
       7/31/2008                     BUY                         321,000                              6.660
------------------------ ---------------------------- --------------------------------- -----------------------------------
       8/29/2008                    SELL                          (5,100)                             6.790
------------------------ ---------------------------- --------------------------------- -----------------------------------
       8/29/2008                     BUY                           5,100                              6.790
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/05/2008                    SELL                        (200,000)                             6.074
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/08/2008                    SELL                         (70,000)                             5.621
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/08/2008                    SELL                        (140,000)                             5.574
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/08/2008                    SELL                         (75,000)                             5.610
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/09/2008                    SELL                        (125,000)                             5.336
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/09/2008                    SELL                         (55,000)                             5.393
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/09/2008                    SELL                         (45,000)                             5.333
------------------------ ---------------------------- --------------------------------- -----------------------------------






                                                    Schedule B
                                                    ----------


                                (Transactions by the Offshore Fund in Common Stock
                                             during the past 60 days)


         Date                   Transaction                       Shares                       Price Per Share($)
         ----                   -----------                       ------                       ------------------

------------------------ ---------------------------- --------------------------------- -----------------------------------
                                                                               
       7/31/2008                     BUY                          110,500                             6.660
------------------------ ---------------------------- --------------------------------- -----------------------------------
       8/29/2008                    SELL                          (1,900)                             6.790
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/05/2008                    SELL                         (140,100)                            6.074
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/08/2008                    SELL                          (45,900)                            5.621
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/08/2008                    SELL                          (91,900)                            5.574
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/08/2008                    SELL                          (49,300)                            5.610
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/09/2008                    SELL                          (80,700)                            5.336
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/09/2008                    SELL                          (36,200)                            5.393
------------------------ ---------------------------- --------------------------------- -----------------------------------
       9/09/2008                    SELL                          (29,600)                            5.333
------------------------ ---------------------------- --------------------------------- -----------------------------------