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                                                                  EXHIBIT 3.3(a)

                         CERTIFICATE OF INCORPORATION

                                      OF

                    AOR MANAGEMENT COMPANY OF ARIZONA, INC.



                                   ARTICLE I

     The name of the corporation is AOR MANAGEMENT COMPANY OF ARIZONA, INC. (the
"Corporation").

                                  ARTICLE II

     The address of the Corporation's registered office, in the County of Kent,
is 32 Loockerman Square, Suite L-100, Dover, Delaware 19904. The name of the
registered agent at that address is The Prentice-Hall Corporation System, Inc.

                                  ARTICLE III

     The nature of the business or purpose to be conducted or promoted by the
Corporation is to engage in any lawful business, act or activity for which
corporations may be organized under the General Corporation Law of the State of
Delaware.

                                  ARTICLE IV

     The total number of shares of all classes of stock which the Corporation
shall have authority to issue is one thousand (1,000), all of which shall be
common stock, $.01 par value per share ("Common Stock").

                                   ARTICLE V

     The Board of Directors is expressly authorized to adopt, amend, alter or
repeal the bylaws of the Corporation.

                                  ARTICLE VI

     The Corporation shall have the right, subject to any express provisions or
restrictions contained in this certificate of incorporation from time to time,
to amend this certificate of incorporation or any provision hereof in any manner
now or hereafter provided by law, and all rights and powers at any time
conferred upon the directors or stockholders of the Corporation by this
certificate of incorporation or any amendment hereto are subject to such right
of the Corporation.
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                                  ARTICLE VII

     The number of directors of the Corporation shall be determined in
accordance with the Corporation's bylaws. The number of directors constituting
the initial board of directors of the Corporation shall be three (3), and the
names and mailing addresses of the persons who are to serve as its directors
until the first annual meeting of its stockholders, or until their respective
successors are duly elected and qualified, are as follows:

          Name                                 Address
          ----                                 -------

          R. Dale Ross                         17001 Northchase Blvd., Suite 330
                                               Houston, Texas 77060

          Lloyd Everson, M.D.                  17001 Northchase Blvd., Suite 330
                                               Houston, Texas 77060

          L. Fred Pounds                       17001 Northchase Blvd., Suite 330
                                               Houston, Texas 77060

                                 ARTICLE VIII

     No director shall be personally liable to the Corporation or its
stockholders for monetary damages for breach of fiduciary duty as a director,
except for liability (i) for any breach of the director's duty of loyalty to the
Corporation or its stockholders, (ii) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law, or (iv) for any transaction
from which the director derived an improper personal benefit.

     If the Delaware General Corporation Law is hereafter amended to authorize
the further elimination or limitation of the liability of a director, then the
liability of a director of the Corporation shall be eliminated or limited to the
fullest extent permitted by the Delaware General Corporation Law, as so amended.

     No repeal or modification of the foregoing provisions of this Article VIII
by the stockholders of the Corporation shall adversely affect any right or
protection of a director of the Corporation existing at the time of such repeal
or modification.

                                  ARTICLE IX

     Elections of directors of the Corporation need not be by written ballot.

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                                   ARTICLE X

     The name and mailing address of the incorporator is as follows:

          Name                                 Mailing Address
          ----                                 ---------------

          Lisa Newburn                         700 Louisiana, Suite 1900
                                               Houston, Texas 77002

     I, the undersigned, being the incorporator herein before named, for the
purpose of forming a corporation pursuant to the General Corporation Law of the
State of Delaware, do make this certificate, hereby declaring that this is my
act and deed and that the facts herein stated are true and accordingly have
hereunder set my hand this 13th day of December, 1994.



                                             ___________________________________
                                             Lisa Newburn, Incorporator

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