Exhibit 5.1

October 31, 2007

Main +1.206.447.0900
Fax +1.206.447.0849

26025-0033

Washington Mutual, Inc.

1201 Third Avenue

Seattle, Washington 98101

Re:

Washington Mutual, Inc. – Public Offering of

$500,000,000 principal amount of 7.250% Subordinated Notes due November 1, 2017

Ladies and Gentlemen:

We have acted as counsel to Washington Mutual, Inc., a Washington corporation (the “Company”), in connection with the filing by the Company with the Securities and Exchange Commission (the “Commission”) pursuant to the Securities Act of 1933, as amended (the “Securities Act”) of (i) a Registration Statement on Form S-3, File No. 333-109929, on January 9, 2006 (the “Registration Statement”), which Registration Statement contained the Company’s prospectus dated January 9, 2006 (the “Base Prospectus”) and (ii) the Company’s final prospectus supplement describing the offering by the Company of $500,000,000 principal amount of 7.250% Subordinated Notes due November 1, 2017 (the “Securities”), dated October 25, 2007 and filed with the Commission on October 29, 2007, pursuant to Rule 424(b) of the rules and regulations of the Commission under the Act (the “Final Prospectus Supplement” and, together with the Base Prospectus, the “Final Prospectus”), registering the sale of the Securities. The Securities will be issued pursuant to a Subordinated Debt Securities Indenture, dated as of April 4, 2000, between the Company and The Bank of New York (as successor to Harris Trust and Savings Bank), as trustee, as supplemented by the First Supplemental Indenture dated August 1, 2002 and Second Supplemental Indenture dated March 16, 2004 (the “Indenture”).

We have assumed the authenticity of all records, documents and instruments submitted to us as originals, the genuineness of all signatures, the legal capacity of natural persons and the conformity to the originals of all records, documents and instruments submitted to us as copies. We have based our opinion upon our review of the following records, documents, instruments and certificates and such additional certificates relating to factual matters as we have deemed necessary or appropriate for our opinion:

(a)

The Registration Statement;

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Washington Mutual, Inc.

October 31, 2007

Page 2

(b)

The Indenture;

(c)

The Final Prospectus;

(d)

The form of the Securities;

(c)

The Amended and Restated Articles of Incorporation of the Company, as amended, filed with the Washington Secretary of State, and certified to us by an officer of the Company as being complete and in full force and effect as of the date of this opinion;

(e)

A Certificate of Existence/Authorization relating to the Company issued by the Washington Secretary of State, dated October 31, 2007;

(f)

The bylaws of the Company, as amended, certified to us by an officer of the Company as being complete and in full force and effect as of the date of this opinion;

(g)

Records certified to us by an officer of the Company as constituting all records of proceedings and actions of the board of directors of the Company relating to the issuance of the Securities by the Company; and

(h)

A certificate of an officer of the Company as to certain factual matters.

II.

This opinion is limited to the federal laws of the United States of America and the laws of the State of New York and State of Washington, and we disclaim any opinion as to the laws of any other jurisdiction. We express no opinion as to the applicable choice of law rules that may affect the interpretation or enforcement of the Securities. We further disclaim any opinion as to any statute, rule, regulation, ordinance, order or other promulgation of any regional or local governmental body or as to any related judicial or administrative opinion.

III.

Based upon the foregoing and our examination of such questions of law as we have deemed necessary or appropriate for the purpose of our opinion, and subject to the limitations and qualifications expressed herein, it is our opinion that the Securities have been duly authorized and, upon authentication of the Securities in accordance with the terms of the Indenture and delivery of and payment therefor, as contemplated by the Final Prospectus, will constitute valid and binding obligations of the Company, enforceable against the Company in accordance with their terms, subject, as to enforcement, (i) to bankruptcy, insolvency, reorganization, arrangement, moratorium and other laws of general applicability relating to or affecting creditors’ rights and (ii) to general principles of equity, whether such enforceability is considered in a proceeding in equity or at law.

Washington Mutual, Inc.

October 31, 2007

Page 3

IV.

We further advise you that:

As noted, the enforceability of the Securities is subject to the effect of general principles of equity. As applied to the Securities, these principles will require the parties thereto to not invoke penalties for defaults that bear no reasonable relation to the damage suffered or that would otherwise work a forfeiture.

The effectiveness of indemnities, rights of contribution, exculpatory provisions, choice of venue or jurisdiction provisions, waiver of jury trials, and waivers of the benefits of statutory provisions may be limited on public policy grounds.

Provisions of the Securities requiring that waivers must be in writing may not be binding or enforceable if a non-executory oral agreement has been created modifying any such provision or an implied agreement by trade practice or course of conduct has given rise to a waiver.

This opinion is rendered to you in connection with the filing of the Registration Statement and is solely for your benefit and the benefit of the purchasers of the Securities. We consent to the filing of this letter as an exhibit to the Registration Statement and to reference our firm in the Registration Statement. This opinion may not be relied upon by any other person, firm, corporation or other entity without our prior written consent. We disclaim any obligation to advise you of any change of law that occurs, or any facts of which we become aware, after the date of this opinion.

Very truly yours,

/s/ HELLER EHRMAN LLP