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                                                                   EXHIBIT 10.18

                FIRST AMENDMENT TO EQUITY OFFICE PROPERTIES TRUST
                 1997 NON-QUALIFIED EMPLOYEE SHARE PURCHASE PLAN
                                FEBRUARY 16, 1999

         WHEREAS, Equity Office Properties Trust ("Equity Office") has adopted
the Equity Office Properties Trust 1997 Non-Qualified Employee Share Purchase
Plan, as amended and restated effective January 1, 1998 (the "Plan");

         WHEREAS, Equity Office desires to amend the Plan to (1) change the
Purchase Period thereunder; (2) make an eligible Trustee's election of
additional contributions subject to trading policies established by Equity
Office's Chief Legal Counsel; (3) restrict the time during which a Participant
may withdraw all or part of the contributions made under the Plan; (4) provide
that amounts insufficient for the purchase of a whole Share shall be carried
over into the next Purchase Period; and (5) grant to the Compensation and Option
Committee the authority to amend or terminate the Plan.

         NOW, THEREFORE, Equity Office hereby amends the Plan, effective
February 16, 1999, in the following respects:

         1. Section 2.16 is amended to read as follows:

         "2.16 The term "Purchase Period" shall mean a period set by the
         Committee. Unless changed by the Committee, each Purchase Period shall
         begin and end on the business days coinciding with or immediately
         following these dates:

                  (i)      After January 1, 1998 and before July 1, 1999:

                           January 2 - June 30
                           July 1 - December 31

                  (ii)     Between the period covered by paragraphs (i) and
                           (iii), July 1 - November 30, 1999.

                  (iii)    On or after December 1, 1999:

                           December 1 - May 31
                           June 1 - November 30

         If the above would cause a Purchase Period to begin on the day that its
         preceding Purchase Period ends, then the succeeding Purchase Period
         shall begin on the next business day."

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         2. Section 5(b) and Sections (c) are each amended to read as follows:

         "(b)     Additional Contributions by Eligible Trustees. In addition to
         the contributions made in accordance with paragraph (a) above, a
         Participant (other than a Participant (a "Restricted Participant") who
         is then prevented from trading in Shares under an insider trading
         policy established by the Chief Legal Counsel of Equity Office) who is
         an eligible Trustee may elect to contribute an additional cash amount
         to the Plan at any time prior to the close of a Purchase Period. The
         Participant may contribute such additional cash amount in accordance
         with procedures established by the Plan Administrator.

         (c)      Changes in Contributions and Withdrawals. Except with respect
         to contributions made under paragraph (b) above, a Participant (other
         than a Restricted Participant) shall have the right to amend his or her
         Election Form at any time to reduce or to stop his or her
         contributions, and such election shall be effective as soon as
         practicable after the Plan Administrator actually receives such amended
         Election Form. A Participant (other than a Restricted Participant) also
         shall have the right at any time on or before ten (10) business days
         prior to the last day of a Purchase Period to withdraw (without
         interest) all or any part of the contributions made under paragraphs
         (a) and/or (b) above and credited to his or her Account for such
         Purchase Period. Any such withdrawal shall be deducted from the
         Participant's Account as of the date the Plan Administrator receives
         such amended Election Form, and the actual withdrawal shall be effected
         by the Plan Administrator as soon as practicable after such date."

         3. Section 6(a) is amended to read as follows:

         "(a)     Automatic Purchase. If a Participant is an Eligible Employee
         or an Eligible Trustee through the end of a Purchase Period, or if a
         balance was retained for such Eligible Employee or Eligible Trustee in
         accordance with Section 5(e), the balance that remains credited to his
         or her Account at the end of such Purchase Period shall automatically
         be applied to purchase the maximum number of whole Shares at the
         Purchase Price established for such Purchase Period. Such Shares shall
         be purchased on behalf of the Participant by operation of this Plan and
         credited to the Participant's Account. The balance of the Participant's
         account shall not be used to purchase fractional Shares. Any amounts
         which are insufficient to purchase a whole Share shall remain in the
         Participant's Account and shall be applied to purchase Shares in the
         next Purchase Period."

         4. Section 13 is amended to read as follows:

         "This Plan may be amended by the Board or the Committee from time to
         time to the extent that the Board or Committee deems necessary or
         appropriate, and any such amendment shall be subject to the approval of
         Equity Office's shareholders to the extent such approval is required
         under the laws of the State of Maryland;

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         provided, however, that no amendment shall be retroactive unless the
         Board or the Committee in its discretion determines that the
         retroactivity of such amendment is in the best interest of Equity
         Office or such amendment is required by applicable law to be
         retroactive. The Board or Committee may also terminate this Plan and
         any Purchase Period (together with any related contributions) at any
         time; provided, however, that no such termination shall be retroactive
         unless the Board or the Committee determines that applicable law
         requires a retroactive termination."

         IN WITNESS WHEREOF, this Amendment has been executed by the duly
authorized officers of Equity Office, this 16th day of February, 1999.

                                    EQUITY OFFICE PROPERTIES TRUST

                                             By: /s/ Stanley M. Stevens
                                                 -------------------------------
                                                 Stanley M. Stevens
                                                 Executive Vice President, Chief
                                                 Legal Counsel and Secretary