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

April 26, 2007
Date of Report (date of earliest event reported)

WAMU ASSET ACCEPTANCE CORP.

as Depositor under a
Pooling and Servicing Agreement
dated as of April 1, 2007
providing for the issuance of

WaMu MORTGAGE PASS-THROUGH CERTIFICATES
SERIES 2007-OA4 TRUST
(Exact name of Registrant as specified in its charter)

Delaware		333-141255		20-2258610
(State or other jurisdiction of incorporation)		(Commission File Number)		(I.R.S. Employer Identification No.)

1301 SECOND AVENUE, WMC 3501A
SEATTLE, WASHINGTON 98101
(Address of principal executive offices and Zip Code)

Registrant's telephone number, including area code: (206) 500-4418

(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.

(d) Exhibits

The following exhibits are filed herewith:

4.1	Pooling and Servicing Agreement by and among WaMu Asset Acceptance 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 April 1, 2007.

4.2

Mortgage Loan Purchase Agreement, dated as of October 25, 2005, among WaMu Asset Acceptance Corp., Washington Mutual Bank and Washington Mutual Bank fsb (incorporated herein by reference from Exhibit 4.6 to the Current Report on Form 8-K filed by WaMu Asset Acceptance Corp. on November 8, 2005 with respect to Registration Statement No. 333-123034).

4.3

Amended and Restated Administrative Agent Agreement, dated as of February 1, 2005, between Washington Mutual Bank and Washington Mutual Mortgage Securities Corp. (incorporated herein by reference from Exhibit 4.9 to the Current Report on Form 8-K filed by WaMu Asset Acceptance Corp. on March 6, 2006 with respect to Registration Statement No. 333-130795).

99.1

Excerpt from Section 2 of the Term Sheet dated April 26, 2007 between Washington Mutual Bank, as seller, and WaMu Asset Acceptance Corp., as purchaser. For a form of term sheet, see Exhibit B to Exhibit 4.6 to to the Current Report on Form 8-K filed by WaMu Asset Acceptance Corp. on November 8, 2005 with respect to Registration Statement No. 333-123034.

99.2	Novation confirmation regarding interest rate cap transaction, dated as of April 26, 2007, among The Bank of New York, Washington Mutual Bank and LaSalle Bank National Association, as trustee on behalf of the trust.

The Mortgage Loan Schedule, included as Exhibit D to the Pooling and Servicing Agreement, has 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.,

        John Ganzer
        Washington Mutual Mortgage Securities Corp.
        75 N. Fairway Drive,VHF2A01
        Vernon Hills, IL 60061
        Telephone: (847) 549-3113
        Facsimile:     (847) 549-3680

in the case of LaSalle Bank National Association,

        Stefanie Edwards
        LaSalle Bank National Association
        135 S. LaSalle Street, Suite 1511
        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.


		WAMU ASSET ACCEPTANCE CORP.
Date: May 11, 2007	By:	/s/ Richard Careaga Richard Careaga First Vice President (Authorized Officer)

Exhibit Index

4.1	Pooling and Servicing Agreement by and among WaMu Asset Acceptance 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 April 1, 2007.

4.2

4.3

99.1

99.2	Novation confirmation regarding interest rate cap transaction, dated as of April 26, 2007, among The Bank of New York, Washington Mutual Bank and LaSalle Bank National Association, as trustee on behalf of the trust.

WaMu Mortgage Pass-Through Certificates, Series 2007-OA4 8-K