EXHIBIT 8.1  Sullivan &
  Worcester LLP
  One Post Office Square
  Boston, MA 02109
  
  T 617 338 2800
  F 617 338 2880
  www.sandw.com
  February 22, 2010  Government Properties
Income Trust 400 Centre Street Newton,
Massachusetts  02458  Ladies and Gentlemen:  The
following opinion is furnished to Government Properties Income Trust, a
Maryland real estate investment trust (the Company), to be filed with the
Securities and Exchange Commission (the SEC) as Exhibit 8.1 to the
Companys Annual Report on Form 10-K for the year ended December 31,
2009 (the Form 10-K) under the Securities Exchange Act of 1934, as
amended.  We
have acted as counsel for the Company in connection with the preparation of the
Form 10-K, and we have reviewed originals or copies of such corporate
records, such certificates and statements of officers of the Company and of
public officials, and such other documents as we have considered relevant and
necessary in order to furnish the opinion hereinafter set forth.  In doing so, we have assumed the genuineness
of all signatures, the legal capacity of natural persons, the authenticity of
all documents submitted to us as originals, the conformity to original
documents of all documents submitted to us as copies, and the authenticity of
the originals of such documents. 
Specifically, and without limiting the generality of the foregoing, we
have reviewed:  (i) the amended and
restated declaration of trust and the amended and restated by-laws of the
Company, each as amended to date; and (ii) the sections of Item 1 of the Form 10-K
captioned Federal Income Tax Considerations and ERISA Plans, Keogh Plans and
Individual Retirement Accounts.  The
opinion set forth below is based upon the Internal Revenue Code of 1986, as
amended, the Treasury Regulations issued thereunder, published administrative
interpretations thereof, and judicial decisions with respect thereto, all as of
the date hereof (collectively, Tax Laws), and upon the Employee Retirement
Income Security Act of 1974, as amended, the Department of Labor regulations
issued thereunder, published administrative interpretations thereof, and
judicial decisions with respect thereto, all as of the date hereof
(collectively, ERISA Laws).  No
assurance can be given that Tax Laws or ERISA Laws will not change.  In preparing the discussions with respect to
Tax Laws matters and ERISA Laws matters in the  BOSTON NEW YORK WASHINGTON, DC


sections of Item 1 of the Form 10-K captioned Federal
Income Tax Considerations and ERISA Plans, Keogh Plans and Individual
Retirement Accounts, we have made certain assumptions therein and expressed
certain conditions and qualifications therein, all of which assumptions,
conditions and qualifications are incorporated herein by reference.  With respect to all questions of fact on
which our opinion is based, we have assumed the initial and continuing truth,
accuracy and completeness of:  (i) the
information set forth in the Form 10-K and in the exhibits thereto; and (ii) representations
made to us by officers of the Company or contained in the Form 10-K and in
the exhibits thereto, in each such instance without regard to qualifications
such as to the best knowledge of or in the belief of.  We have not independently verified such
information.  We
have relied upon, but not independently verified, the foregoing
assumptions.  If any of the foregoing
assumptions are inaccurate or incomplete for any reason, or if the transactions
described in the Form 10-K or the exhibits thereto have been consummated
in a manner that is inconsistent with the manner contemplated therein, our
opinion as expressed below may be adversely affected and may not be relied
upon.  Based
upon and subject to the foregoing, we are of the opinion that the discussions
with respect to Tax Laws matters and ERISA Laws matters in the sections of Item
1 of the Form 10-K captioned Federal Income Tax Considerations and ERISA
Plans, Keogh Plans and Individual Retirement Accounts in all material respects
are accurate and fairly summarize the Tax Laws issues and the ERISA Laws issues
addressed therein, and hereby confirm that the opinions of counsel referred to
in said sections represent our opinions on the subject matter thereof.  Our
opinion above is limited to the matters specifically covered hereby, and we have
not been asked to address, nor have we addressed, any other matters or any
other transactions.  Further, we disclaim
any undertaking to advise you of any subsequent changes of the matters stated,
represented or assumed herein or any subsequent changes in Tax Laws or ERISA
Laws.  This opinion is intended solely for the benefit and
use of the Company, and is not to be used, released, quoted, or relied upon by
anyone else for any purpose (other than as required by law) without our prior
written consent.  We hereby consent to
the filing of a copy of this opinion as an exhibit to the Form 10-K, and
to the references to our firm in the Form 10-K.  In giving such consent, we do not thereby
admit that we come within the category of persons whose consent is required
under Section 7 of the Securities Act of 1933, as amended, or under the rules and
regulations of the SEC promulgated thereunder.  Very truly yours,/s/   Sullivan
  & Worcester LLPSULLIVAN & WORCESTER LLP  2