SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-K
CURRENT REPORT

Pursuant to Section 13 or 15(d) of the
Securities Exchange Act of 1934

May 25, 2005
Date of Report (date of earliest event reported)

WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.

as Depositor under a
Pooling and Servicing Agreement
dated as of May 1, 2005
providing for the issuance of

WASHINGTON MUTUAL MORTGAGE PASS-THROUGH CERTIFICATES,
WMALT SERIES 2005-4
(Exact name of Registrant as specified in its charter)

Delaware		333-103345		94-2528990
(State or other jurisdiction of incorporation)		(Commission File Number)		(I.R.S. Employer Identification No.)

1201 THIRD AVENUE, WMT 1706
SEATTLE, WASHINGTON 98101
(Address of principal executive offices and Zip Code)

Registrant's telephone number, including area code: (206) 377-8555

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

o Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

o Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

o Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

o Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

SECTION 9 FINANCIAL STATEMENTS AND EXHIBITS

Item 9.01. Financial Statements and Exhibits.

The following exhibit is filed herewith:

4.1	Pooling and Servicing Agreement by and among Washington Mutual Mortgage Securities Corp., as Depositor, Washington Mutual Bank, as Servicer, LaSalle Bank National Association, as Trustee, and Christiana Bank & Trust Company , as Delaware Trustee, dated as of May 1, 2005.

The definition of Class C-Y Principal Reduction Amounts, included as Appendix 1 to the Pooling and Servicing Agreement, and the Mortgage Loan Schedule, included as Exhibit D to the Pooling and Servicing Agreement, have been intentionally omitted from this filing. Copies may be obtained from Washington Mutual Mortgage Securities Corp. or LaSalle Bank National Association by contacting,:

in the case of Washington Mutual Mortgage Securities Corp.,

        Laura Kelsey
        Master Servicing Department
        Washington Mutual Mortgage Securities Corp.
        75 N. Fairway Drive,VHF2A01
        Vernon Hills, IL 60061
        Telephone: (847) 393-5198
        Facsimile:     (847) 549-2997

in the case of LaSalle Bank National Association,

        Stefanie Edwards
        LaSalle Bank National Association
        135 S. LaSalle Street, Suite 1625
        Chicago, IL 60603
        Telephone:  (312) 904-8975
        Facsimile:    (312) 904-2084

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

		WASHINGTON MUTUAL MORTGAGE SECURITIES CORP.
Date: June 9, 2005		By:		/s/ David H. Zielke David H. Zielke First Vice President and Counsel (Authorized Officer)

Exhibit Index

4.1	Pooling and Servicing Agreement by and among Washington Mutual Mortgage Securities Corp., as Depositor, Washington Mutual Bank, as Servicer, LaSalle Bank National Association, as Trustee, and Christiana Bank & Trust Company , as Delaware Trustee, dated as of May 1, 2005.

Washington Mutual Mortgage Pass-Through Certificates, WMALT 2005-4 8-K