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) June 6, 2006

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:

Item 2.03 Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant.

On June 6, 2006, Washington Real Estate Investment Trust (“WRIT”) completed the public offering of $100,000,000 aggregate principal amount of senior notes (the “Notes”) pursuant to an Underwriting Agreement dated June 1, 2006, between WRIT, Credit Suisse Securities (USA) LLC, Wells Fargo Securities, LLC and J.P. Morgan Securities Inc.

The Notes were issued on June 6, 2006 pursuant to a Registration Statement on Form S-3 (File No. 333-114410), filed with the Securities and Exchange Commission (the “SEC”) on April 12, 2004, and declared effective on April 29, 2004. A Prospectus Supplement dated June 1, 2006 relating to the Notes (the “Prospectus Supplement”) and supplementing the Prospectus dated April 29, 2004 (the “Prospectus”) was filed with the SEC on June 2, 2006 pursuant to Rule 424(b)(5) under the Securities Act of 1933, as amended.

The Notes were issued in a single series of $100,000,000 aggregate principal amount 5.95% Senior Notes due June 15, 2011, at a price of 99.951% of their principal amount. Interest on the Notes is payable semiannually in arrears on June 15 and December 15 of each year, beginning December 15, 2006. Interest on the Notes will accrue from June 6, 2006. The Notes will rank equally with all other unsecured senior indebtedness of WRIT. The Notes may be redeemed in whole or in part at any time before maturity at the redemption price described in the Prospectus Supplement and will not be subject to any sinking fund. Descriptions of the terms of the Notes are included under the caption “Description of the Notes” in the Prospectus Supplement and under the caption “Description of Debt Securities” in the Prospectus. The form of the Notes and the Officers’ Certificate establishing the terms of the Notes are attached to this Current Report on Form 8-K as Exhibits 4.1 and 4.2, respectively.

Item 9.01. Financial Statements and Exhibits.

(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.

June 6, 2006

Exhibit Index