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

Date of Report (Date of earliest event reported) April 30, 2009

WASHINGTON REAL ESTATE INVESTMENT TRUST

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code (301) 984-9400

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:

The response set forth below under Item 8.01 is incorporated by reference herein.

On April 30, 2009, Washington Real Estate Investment Trust (“WRIT”) entered into an Underwriting Agreement (the “Underwriting Agreement”) with Wachovia Capital Markets, LLC, Citigroup Global Markets Inc., and Raymond James & Associates, Inc. as representatives of the several underwriters named therein (collectively, the “Underwriters”), in connection with the offer and sale of 5,000,000 of WRIT’s common shares of beneficial interest (the “Shares”). In addition to the Shares, WRIT granted the Underwriters an over-allotment option to purchase up to an additional 750,000 shares.

WRIT and the Underwriters intend to consummate the sale and purchase of the Shares pursuant to the Underwriting Agreement on May 5, 2009.

The Shares are described in WRIT’s prospectus supplement dated April 30, 2009 (the “Prospectus Supplement”), which supplements WRIT’s prospectus dated August 28, 2008 filed with the Securities and Exchange Commission (the “SEC”) pursuant to a Registration Statement on Form S-3 (File No. 333-136921), filed with the SEC (the “Registration Statement”). The Prospectus Supplement was filed with the SEC on April 30, 2009, pursuant to Rule 424(b)(5) under the Securities Act of 1933, as amended.

In connection with the offering of the Shares, WRIT is filing certain exhibits as part of this Form 8-K that are incorporated by reference in their entirety in the Registration Statement.

(c) Exhibits

The following exhibits are filed with this report on Form 8-K:

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.

April 30, 2009

Exhibit Index