EXHIBIT 4.1

[Face of Certificate]

Number *0*                                                         Shares *0*

                                                      See Reverse for
                                                      Important Notice
                                                      on Transfer Restrictions
                                                      and Other Information

                     THIS CERTIFICATE IS TRANSFERABLE          CUSIP _________
                    IN THE CITIES OF _________________

                    CORPORATE OFFICE PROPERTIES TRUST
                     a Real Estate Investment Trust
              Formed Under the Laws of the State of Maryland

      THIS CERTIFIES THAT **Specimen**

is the owner of *Zero (0)**

fully paid and nonassessable common shares of beneficial interest, $0.01 par 
value per share, of

                    CORPORATE OFFICE PROPERTIES TRUST

(the "Trust"), transferable on the books of the Trust by the holder hereof in 
person or by its duly authorized attorney upon surrender of this Certificate 
properly endorsed.  This Certificate and the shares represented hereby are 
issued and shall be held subject to all of the provisions of the Declaration 
of Trust and Bylaws of the Trust and any amendments thereto.  This 
Certificate is not valid unless countersigned and registered by the Transfer 
Agent and Registrar.

IN WITNESS WHEREOF, the Trust has caused this Certificate to be executed on 
its behalf by its duly authorized officers.

DATED ____________________

Countersigned and Registered:
     Transfer Agent                     [IMPRESSION OF
      and Registrar                       TRUST SEAL]  _________________________
                                                              President

     By:______________________________                 _________________________
               Authorized Signature                           Secretary


 
                                       2

[Reverse of Certificate]

                                IMPORTANT NOTICE

The Trust will furnish to any shareholder, on request and without charge, a 
full statement of the information required by Section 8-203(d) of the 
Corporations and Associations Article of the Annotated Code of Maryland with 
respect to the designations and any preference, conversion and other rights, 
voting powers, restrictions, limitations as to dividends and other 
distributions, qualifications, and terms and conditions of redemption of the 
shares of each class of beneficial interest which the Trust has authority to 
issue and, if the Trust is authorized to issue any preferred or special class 
in series, (i) the differences in the relative rights and preferences between 
the shares of each series to the extent set, and (ii) the authority of the 
Board of Trustees to set such rights and preferences of subsequent series.  
The foregoing summary does not purport to be complete and is subject to and 
qualified in its entirety by reference to the Declaration of Trust of the 
Trust, a copy of which will be sent without charge to each shareholder who so 
requests.  Such request must be made to the Secretary of the Trust at its 
principal office or to the Transfer Agent.

The shares represented by this Certificate are subject to restrictions on 
Beneficial Ownership, Constructive Ownership and Transfer for the purpose of 
the Trust's maintenance of its status as a real estate investment trust (a 
"REIT") under the Internal Revenue Code of 1986, as amended (the "Code").  
Subject to certain further restrictions and except as expressly provided in 
the Declaration of Trust of the Trust, (i) no Person may Beneficially Own or 
Constructively Own Common Shares of the Trust in excess of 9.8 percent (in 
value or number of shares) of the outstanding Common Shares of the Trust 
unless such Person is an Excepted Holder or a Permitted Holder (in which case 
the Excepted Holder Limit shall be applicable); (ii) no Person may 
Beneficially Own or Constructively Own Equity Shares of the Trust in excess 
of 9.8 percent of the value of the total outstanding Equity Shares of the 
Trust, unless such Person is an Excepted Holder or a Permitted Holder (in 
which case the Excepted Holder Limit shall be applicable);(iii) no Person may 
Beneficially Own or Constructively Own Equity Shares that would result in the 
Trust being "closely held" under Section 856(h) of the Code or otherwise 
cause the Trust to fail to qualify as a REIT; and (iv) no Person may Transfer 
Equity Shares if such Transfer would result in Equity Shares or the Trust 
being owned by fewer than 100 Persons.  



                                       3

Any Person who Beneficially Owns or Constructively Owns or attempts to 
Beneficially Own or Constructively Own Equity Shares which cause or will 
cause a Person to Beneficially Own or Constructively Own Equity Shares in 
excess or in violation of the above limitations must immediately notify the 
Trust.  If any of the restrictions on transfer or ownership are violated, the 
Equity Shares represented hereby will be automatically transferred to a 
Trustee of a Charitable Trust for the benefit of one or more Charitable 
Beneficiaries.  In addition, upon the occurrence of certain events, attempted 
Transfers in violation of the restrictions described above may be void ab 
initio.  All capitalized terms in this legend have the meanings defined in 
the Declaration of Trust of the Trust, as the same may be amended from time 
to time, a copy of which, including the restrictions on transfer and 
ownership, will be furnished to each holder of Equity Shares of the Trust on 
request and without charge.  Such request must be made to the Secretary of 
the Trust at its principal office or to the Transfer Agent.

      KEEP THIS CERTIFICATE IN A SAFE PLACE.  IF IT IS LOST, STOLEN
      OR DESTROYED, THE TRUST WILL REQUIRE A BOND OF INDEMNITY AS A
         CONDITION TO THE ISSUANCE OF A REPLACEMENT CERTIFICATE.

     The following abbreviations, when used in the inscription on the face of 
this Certificate, shall be construed as though they were written out in full 
according to applicable laws or regulations:

TEN COM - as tenants in common           UNIF GIFT MIN ACT_____ Custodian _____
TEN ENT - as tenants by the entireties                    (cust)         (minor)
JT TEN  - as joint tenants with right       under Uniform Gifts to Minors Act of
          of survivorship and not as                     _______________________
          tenants in common                              (State)

                                Additional abbreviations may also be used though
                                not in the above list.


 
                                       4

FOR VALUE RECEIVED, _____________________________ HEREBY SELLS, ASSSIGNS AND 
TRANSFERS UNTO

_______________________________________________________________________________
(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

_______________________________________________________________________________
(PLEASE INSERT SOCIAL SECURITY OR OTHER IDENTIFYING NUMBER OF ASSIGNEE)

__________________________ (__________________________) shares of beneficial 
interest of the Trust represented by this Certificate and do hereby 
irrevocably constitute and appoint _______________________________ attorney 
to transfer the said shares on the books of the Trust, with full power of 
substitution in the premises.

Dated _________________________    ____________________________________________

                                   NOTICE: THE SIGNATURE TO THIS ASSIGNMENT 
                                   MUST CORRESPOND WITH THE NAME AS WRITTEN 
                                   UPON THE FACE OF THIS CERTIFICATE IN 
                                   EVERY PARTICULAR, WITHOUT ALTERNATION OR 
                                   ENLARGEMENT OR ANY CHANGE WHATEVER.