<PAGE>
                                                                  Exhibit 10.13


                            CONSULTING AGREEMENT FOR
                      PHYSICIAN PRACTICE MANAGEMENT ASSETS

     THIS CONSULTING AGREEMENT ("Agreement") is entered into on December 8, 
1998 between PhyMatrix Corp. ("Company") and RAM Advisors Inc., ("RAM").

     This Agreement will permit RAM to act as a consultant to, or perform
services for the Company, upon the following terms and conditions:

     1.   RAM agrees to perform the following services for the Company:
              
                   To act as a consultant in the negotiation and workout of the 
                   physician practice management assets of the Company which are
                   not being divested by Smith Barney.

     2.   In exchange for these consulting services, the Company agrees to
          compensate RAM in the amount of Three Hundred and Ninety Thousand
          Dollars ($390,000.00) to be paid in the following manner: One Hundred
          Thousand Dollars ($100,000.00) at the time of execution of this
          Agreement, with the remaining Two Hundred Ninety Thousand Dollars
          ($290,000.00) plus the Interest Factor payable in six (6) equal
          monthly payments of principal and interest beginning on January 1,
          1999 and ending on June 1, 1999. The Interest Factor shall be equal to
          the Prime Rate of Interest charged be Nations Bank on the date of
          execution of this Agreement plus two percent (2%), multiplied by the
          unpaid portion of the compensation payable to RAM over the
          aforementioned six (6) month period. The Interest Factor shall be
          adjusted as payments are made under this Agreement; in which case, the
          portion of the six (6) equal payments attributable to interest shall
          be adjusted to reflect the same. Notwithstanding the foregoing, in the
          event that the Company closes an agreement during the aforementioned
          period with American Regional Medical or Atlanta Gastroenterology
          Associates, there shall be an immediate acceleration of Fifty Thousand
          Dollars ($50,000.00) of the payments due by the Company to RAM under
          this Agreement for either such agreement entered into by the Company.
          Thus, if the Company enters into settlement agreements with American
          Regional Medical and Atlanta Gastroenterology Associates, there shall
          be immediate acceleration of One Hundred Thousand Dollars
          ($100,000.00) of payments due by the Company to RAM. In addition, in
          the event the Company closes an agreement with the Osler Medical
          Group, there shall be an immediate acceleration of One Hundred
          Thousand Dollars ($100,000.00) of the payments due to RAM under this
          Agreement; in which case One Hundred Thousand Dollars ($100,000.00)
          shall be immediately payable to RAM. Any payments due under this
          Agreement may be accelerated at the option of the Company. Any
          acceleration of any payment made by the Company under this Agreement
          shall offset on a pro-rata basis the remaining payments due to RAM
          under this Agreement. RAM shall be entitled to claim and be reimbursed
          for any and all necessary business expenses incurred in connection
          with the performance of the services herein within fifteen (15)
          days after

                                       1

<PAGE>

          submission of such expenses to the Company.

     3.   The term of this Agreement is for a period beginning upon execution of
          this Agreement and ending on June 1, 1999. Such term may be extended
          only by mutual agreement in writing between the parties.

     4.   RAM shall be and remain an independent contractor. As such, the
          Company shall not deduct from fees paid under this Agreement any
          statutory deductions or unemployment, withholding or social security
          taxes. RAM agrees that neither it nor any of its employees, agents and
          independent contractors shall have any authority or shall represent
          themselves as having any authority to bind the Company in any manner
          whatsoever.

     5.   If any of the above services are performed on the Company's premises,
          RAM agrees to comply with all applicable state and federal rules and
          regulations as to safety, OSHA, etc. RAM also agrees that any
          employees employed by it in the provision of services under this
          Agreement will also comply with such rules and regulations.

     6.   During the term of this agreement, RAM may provide services to other
          parties so long as those services, in the reasonable opinion of RAM,
          do not interfere with the services to be rendered to the Company under
          this Agreement and the Divestiture Agreement.

     7.   Any information (written, oral or observed) received by RAM during the
          course of providing services to the Company will be deemed to be
          confidential. This information may only be used in the provision of
          services under this Agreement and may not be revealed to any third
          parties during this Agreement or after its expiration without the
          prior written consent of the Company.

     8.   RAM's rights under this Agreement may not be assigned without prior
          written consent of the Company.

     9.   Any dispute, controversy, claim or disagreement arising out of or
          relating to this Agreement in any way shall be conclusively settled by
          arbitration to be held in the City of West Palm Beach, Florida in
          accordance with the procedural rules of the American Arbitration
          Association. Judgment upon the decision and award of the arbitrator(s)
          may be entered in any court having jurisdiction thereof. In addition,
          the parties agree that the arbitrator(s) shall have the exclusive
          power to consider and issue requests for injunctive relief to prevent
          any breach of this Agreement or to enforce specifically the terms and
          provisions of this Agreement. The costs, attorney's fees and expenses
          of such arbitration that are incurred by the prevailing party shall be
          awarded by the arbitrator to the prevailing party. Notwithstanding the
          foregoing, in the event the Company fails to timely make any payment
          required to be made to RAM under this Agreement, interest on the
          unpaid amount of

 
                                      2

<PAGE>

          compensation due to RAM under this Agreement shall accrue at the rate
          of fifteen percent (15%) per annum from the date of nonpayment and RAM
          shall be entitled to all costs and attorney's fees incurred in
          connection with collection of any payment which was not timely made to
          it under this Agreement.

     10.  This Agreement shall be governed by the laws of the State of Florida.

     11.  This Agreement constitutes the entire agreement between the parties,
          and any amendment to this Agreement must by in writing and signed by
          both parties.

     IN WITNESS WHEREOF, the undersigned hereunto set their hands on the 
dates shown below.

                                             RAM Advisors, Inc.

                                             By:    /s/ Robert A. Miller
                                                    ---------------------
                                             Title:

                                             PhyMatrix Corp.

                                             By:    /s/ Abraham Gosman
                                                    ------------------
                                             Title:

READ AND AGREED TO:

/s/ ABRAHAM GOSMAN
------------------------------
   ABRAHAM GOSMAN

       12/8/98
------------------------------
DATE












                                       3