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                                                                    EXHIBIT 4.2

                         AMENDMENT TO RIGHTS AGREEMENT


         THIS AMENDMENT TO RIGHTS AGREEMENT ("Amendment"), dated as of May 27,
2004, is between ORTHODONTIC CENTERS OF AMERICA, INC., a Delaware corporation
("OCA"), and EQUISERVE TRUST COMPANY, N.A., as Rights Agent (the "Rights
Agreement").

                                   RECITALS:

         WHEREAS, OCA and the Rights Agent are parties to a Rights Agreement,
dated as of March 3, 2004 ("Rights Agreement");

         WHEREAS, Section 29 of the Rights Agreement (i) permits OCA to amend
the Rights Agreement to add, delete, modify or otherwise amend any provision,
which OCA may deem necessary or desirable, and, (ii) upon the delivery of a
certificate from an appropriate officer of OCA, which states that the proposed
amendment is in compliance with the terms of Section 29 of the Rights Agreement
and, provided such amendment does not change or increase the Rights Agent's
rights, duties, liabilities or obligations thereunder, requires the Rights
Agent to execute such amendment;

         WHEREAS, the Board of Directors of OCA in resolutions duly adopted on
April 30, 2004 has determined that an amendment to the Rights Agreement as set
forth herein is desirable and is consistent with the objectives of the Board of
Directors in connection with the adoption of the Rights Agreement; and

         WHEREAS, the execution and delivery to the Rights Agent of this
Amendment by an appropriate officer of OCA constitutes the delivery of a
certificate by an appropriate officer of OCA that this Amendment complies with
the terms of Section 29 of the Rights Agreement.

         NOW, THEREFORE, in consideration of the premises and the mutual
agreements herein set forth, the parties hereto agree as follows:

                                   AGREEMENT:

         1.       AMENDMENT TO DEFINITION. Section 1(a) of the Rights Agreement
is hereby amended by adding the following as subparagraph (iii) thereof:

                           (iii) no Person which had reported being the
                  Beneficial Owner of more than fifteen percent (15%) but less
                  than twenty percent (20%) of the Voting Shares on a Schedule
                  13G or an amendment to Schedule 13G filed with the Securities
                  and Exchange Commission under the Exchange Act during 2004
                  and prior to the effectiveness of this Agreement on March 3,
                  2004, shall be deemed to be an "Acquiring Person" for
                  purposes of this Agreement, unless and until such time as
                  such Person, together with its Affiliates and Associates,
                  directly or




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                  indirectly, becomes the Beneficial Owner of twenty-five
                  percent (25%) or more of the Voting Shares then outstanding or
                  the Board of Director otherwise determines by resolution duly
                  adopted that such Person shall no longer hereby be exempted
                  from the definition of "Acquiring Person"; provided that this
                  subparagraph (iii) shall not apply to any transferee, acquiror
                  or assignee of any voting shares of which such Person or its
                  Affiliates or Associates is the Beneficial Owner.

         2.       NO OTHER CHANGES. Except as set forth in this Amendment, the
Rights Agreement shall remain in full force and effect as the same was in
effect immediately prior to the date of this Amendment.

         3.       GOVERNING LAW. This Amendment shall be deemed to be a contract
made under the laws of the State of Delaware and for all purposes shall be
governed by and construed in accordance with the laws of such State applicable
to contracts to be made and performed entirely within such State.

         4.       COUNTERPARTS. This Amendment may be executed in any number of
counterparts and each of such counterparts shall for all purposes be deemed to
be an original, and all such counterparts shall together constitute but one and
the same instrument.

         5.       DESCRIPTIVE HEADINGS. Descriptive headings of the several
Sections of this Amendment are inserted for convenience only and shall not
control or affect the meaning or construction of any of the provisions hereof.

         6.       CERTIFICATION. The undersigned officer of OCA certifies by
execution hereof that this Amendment is in compliance with the terms of Section
29 of the Rights Agreement.



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         IN WITNESS WHEREOF, the parties hereto have caused this Amendment to
be duly executed and attested, all as of the day and year first above written.


                                ORTHODONTIC CENTERS OF AMERICA, INC.


                                By: /s/ Bartholomew F. Palmisano, Sr.
                                   ---------------------------------------------
                                   Bartholomew F. Palmisano, Sr.
                                   Chairman of the Board, President and
                                   Chief Executive Officer




                                EQUISERVE TRUST COMPANY, N.A.


                                By: /s/ Thomas F. Tighe
                                   ---------------------------------------------
                                   Thomas F. Tighe
                                   Managing Director




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