<PAGE>

                               FIRST AMENDMENT TO
                           INVESTORS' RIGHTS AGREEMENT

         THIS FIRST AMENDMENT TO INVESTORS' RIGHTS AGREEMENT (this "AGREEMENT")
is entered into as of November 15, 2000, by and between Obagi Medical Products,
Inc., a California corporation (the "COMPANY") (formerly known as OMP
Acquisition Corporation), Mandarin Partners LLC ("MANDARIN") and the Zein and
Samar Obagi Family Trust (the "OBAGI TRUST") (collectively referred to as the
"PARTIES").

                                    RECITALS

         WHEREAS, the Parties entered into an Investors' Rights Agreement, dated
December 2, 1997 (the "INVESTORS' RIGHTS AGREEMENT"); and

         WHEREAS the Parties desire to amend the Investors' Rights Agreement to
increase to three (3) from two (2) the number of registrations (as that term is
defined in the Investors' Right Agreement) filed in compliance with the
Securities Act of 1933 after which the Company shall not be obligated to take
any action to effect any further registrations; and

         WHEREAS the Parties desire to amend the Investors' Rights Agreement to
provide that no Holder (as that term is defined in the Investors' Rights
Agreement) shall be held jointly and severally liable with any other Holder for
any indemnification arising under Section 2.9(b) of the Investors' Rights
Agreement; and

         WHEREAS the Parties desire to amend the Investors' Rights Agreement to
provide that a selling Holder's indemnification obligation under Section 2.9(d)
of the Investors' Rights Agreement shall not exceed the amount of gross proceeds
from the offering received by such selling Holder; and

         WHEREAS the Parties desire to amend the Investors' Rights Agreement to
provide that the Company shall pay all expenses incurred in connection with a
registration requested pursuant to Section 2.11 of the Investors' Rights
Agreement as further described below, but excluding any underwriter's discounts
or commissions associated with Registrable Securities (as that term is defined
in the Investors' Rights Agreement); and

         WHEREAS the Parties desire to amend Section 2.14(a) of the Investors'
Rights Agreement to increase to five (5) the number of years after which no
Holder shall be entitled to exercise any right provided under Section 2 of the
Investors' Rights Agreement following the consummation of the sale of securities
pursuant to a registration statement filed by the Company under the Act, and to
deletes the words "Section 1" and replace such words with "Section 2" to
accurately reflect the intent of the parties.

         NOW, THEREFORE, in consideration of the mutual premises and promises
herein contained and other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the parties hereto agree as
follows:

<PAGE>

                                    AGREEMENT

         1. Section 2.1(d)(i) of the Investors' Rights Agreement is hereby
amended by deleting all of said Section 2.1(d)(i) and replacing it with the
following:

                  "(i) After the Company has effected three (3) registrations
         pursuant to this Section 2.1 and such registrations have been declared
         or ordered effective;".

         2. Section 2.9(b) of the Investors' Rights Agreement is hereby amended
by deleting all of said Section 2.9(b) and replacing it with the following:

                  "(b) To the extent permitted by law, each selling Holder will
         indemnify and hold harmless the Company, each of its directors, each of
         its officers who has signed the registration statement, each person, if
         any, who controls the Company within the meaning of the Act, any
         underwriter, any other Holder selling securities in such registration
         statement and any controlling person of any such underwriter or other
         Holder, against any losses, claims, damages, or liabilities (joint or
         several) to which any of the foregoing persons may become subject,
         under the Act, the 1934 Act or other federal or state law, insofar as
         such losses, claims, damages, or liabilities (or actions in respect
         thereto) arise out of or are based upon any Violation, in each case to
         the extent (and only to the extent) that such Violation occurs in
         reliance upon and in conformity with written information furnished by
         such Holder expressly for use in connection with such registration; and
         each such Holder will pay, as incurred, any legal or other expenses
         reasonably incurred by any person intended to be indemnified pursuant
         to this subsection 2.9(b), in connection with investigation or
         defending any such loss, claim, damage, liability, or action; provided,
         however, that the indemnity agreement contained in this subsection
         2.9(b) shall not apply to amounts paid in settlement of any such loss,
         claim, damage, liability or action if such settlement is effected
         without the consent of the Holder, which consent shall not be
         unreasonably withheld; provided, that, in no event shall any indemnity
         under this subsection 2.9(b) exceed the gross proceeds from the
         offering received by such Holder. In no event shall a selling Holder be
         jointly and severally liable with any other selling Holder for any
         indemnification arising under this Section 2.9(b)."

         3. Section 2.9(d) of the Investors' Rights Agreement is hereby amended
by deleting all of said Section 2.9(d) and replacing it with the following:

                  "(d) If the indemnification provided for in this Section 2.9
         is held by a court of competent jurisdiction to be unavailable to an
         indemnified party with respect to any loss, liability, claim, damage,
         or expense referred to therein, then the indemnifying party, in lieu of
         indemnifying such indemnified party hereunder, shall contribute to the
         amount paid or payable by such indemnified party as a result of such
         loss, liability, claim, damage, or expense in such proportion as is
         appropriate to reflect the relative fault of the indemnifying party on
         the one hand


                                      -2-

<PAGE>

         and of the indemnified party on the other in connection with the
         statements or omissions that resulted in such loss, liability, claim,
         damage, or expense as well as any other relevant equitable
         considerations. The relative fault of the indemnifying party and of the
         indemnified party shall be determined by reference to, among other
         things, whether the untrue or alleged untrue statement of a material
         fact or the omission to state a material fact relates to information
         supplied by the indemnifying party or by the indemnified party and the
         parties' relative intent, knowledge, access to information, and
         opportunity to correct or prevent such statement or omission.
         Notwithstanding any provision to the contrary in this Section 2.9(d),
         in the event that the indemnifying party is a selling Holder, in no
         event shall the selling Holder's obligation to contribute any amounts
         hereunder exceed the amount of gross proceeds from the offering
         received by such Holder."

         4. Section 2.11(c) of the Investors' Rights Agreement is hereby amended
by deleting all of said Section 2.11(c) and replacing it with the following:

                  "(c) Subject to the foregoing, the Company shall file a
         registration statement covering the Registrable Securities and other
         securities so requested to be registered as soon as practicable after
         receipt of the request or requests of the Holders. All expenses
         incurred in connection with a registration requested pursuant to
         Section 2.11, including (without limitation) all registration, filing,
         qualification, printer's and accounting fees and the reasonable fees
         and disbursements of one counsel for the selling Holder or Holders if
         Company counsel does not make itself available for this purpose, and
         counsel for the Company, but excluding any underwriter's discounts or
         commissions associated with Registrable Securities, shall be borne and
         paid for by the Company. Registrations effected pursuant to this
         Section 2.11 shall not be counted as demands for registration or
         registrations effected pursuant to Sections 2.1 or 2.2, respectively."

         5. Section 2.14(a) of the Investors' Rights Agreement is hereby amended
by deleting all of said Section 2.14(a) and replacing it with the following:

                  "(a) No Holder shall be entitled to exercise any right
         provided for in this Section 2 after five (5) years following the
         consummation of the sale of securities pursuant to a registration
         statement filed by the Company under the Act in connection with the
         initial firm commitment underwritten offering of its securities to the
         general public."

         6. EFFECT OF AMENDMENT. All terms and provisions of the Investors'
Rights Agreement shall continue in full force and effect except as expressly
modified in this Agreement. Each reference in the Investors' Rights Agreement to
"this Agreement," "hereunder," "hereof," or words of like import, and each
reference to the Investors' Rights Agreement in any and all instruments or
documents provided for in the Investors' Rights Agreement or delivered or to be
delivered thereunder or in connection therewith, shall, except where the context
otherwise requires, be deemed a reference to the Investors' Rights Agreement as
amended hereby.


                                      -3-

<PAGE>

         7. NO THIRD-PARTY BENEFICIARIES. Nothing expressed or implied in this
Agreement is intended to confer upon any person, other than the parties hereto,
or their respective successors or permitted assigns, any rights, remedies,
obligations or liabilities under or by reason of this Agreement.

         8. COUNTERPARTS. This Agreement may be executed in counterparts, each
of which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

         9. CHOICE OF LAW; HEADINGS. This Agreement shall be governed by and
construed in accordance with the internal laws of the State of California
(regardless of such state's conflict of laws principles), and without reference
to any rules of construction regarding the party responsible for the drafting
hereof. Headings in this Agreement are for the purposes of reference only and
shall not limit or otherwise affect any of the terms hereof.

         10. SUCCESSORS AND ASSIGNS. This Agreement shall be binding upon and
inure to the benefit of the parties hereto and their respective successors and
permitted assigns.



                            [Signature Page Follows]


                                      -4-

<PAGE>

         IN WITNESS WHEREOF, the parties have executed this Agreement on the day
and year first above written.


                                OBAGI MEDICAL PRODUCTS, INC.


                                By:
                                    --------------------------------------
                                              Phillip J. Rose


                                Its:             President
                                    --------------------------------------



                                SHAREHOLDERS:

                                MANDARIN PARTNERS LLC


                                By:
                                   ---------------------------------------
                                                Peter P. Tong

                                Its:              Manager
                                    --------------------------------------


                                ZEIN AND SAMAR OBAGI
                                FAMILY TRUST


                                By:
                                    --------------------------------------
                                            Dr. Zein Obagi

                                Its:            Trustee
                                     -------------------------------------


                                      -5-