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                                                                    EXHIBIT 4.3


April 19, 2002


On Assignment, Inc.
26651 West Agoura Road
Calabasas, California 91302

Gentlemen:

        The undersigned is the record and beneficial owner of capital stock of
Health Personnel Options Corporation, an Ohio corporation ("HPOC"). On
Assignment, Inc., a Delaware corporation ("On Assignment"), HPOC, On Assignment
Acquisition Corp., a subsidiary of On Assignment, the undersigned and certain
other shareholders of HPOC have entered into an Agreement and Plan of Merger
(the "Merger Agreement") dated March 27, 2002. All terms not otherwise defined
herein shall have the same meanings as in the Merger Agreement.

        1. Pursuant to the Merger Agreement and upon the consummation of the
transactions contemplated thereby, the undersigned will receive cash and Parent
Common Stock in exchange for his capital stock of HPOC. The undersigned agrees
that he will not, directly or indirectly, except as otherwise provided herein,
sell, offer to sell, contract to sell, grant any option to purchase or otherwise
transfer or dispose of any shares of Parent Common Stock received by him
pursuant to the Merger (the "Restricted Stock") without the prior written
consent of On Assignment for a period commencing on the Closing Date and ending
twenty-one months from such date (the "Restriction Period"); provided, however,
that the undersigned shall be permitted to sell 25% of the Restricted Stock on
the first anniversary of the Closing Date, and an additional 25% every 90 days
thereafter. Restricted Stock that is no longer subject to the "lock up"
provisions of this letter may be sold by the undersigned at any time thereafter
during the Restriction Period. All sales of Restricted Stock during the
Restriction Period shall be made pursuant to Rule 144 promulgated under the
Securities Act of 1933, as amended (the "Act"). The foregoing shall not restrict
any transfer by will or pursuant to the laws of descent and distribution or to a
trust for the benefit of the undersigned or any member of his family so long as
each and every such transferee, as a condition to the effectiveness of such
transfer, executes and delivers to On Assignment a copy of this letter agreeing
to be bound by the terms hereof.

        2. The undersigned understands that On Assignment will give stop
transfer instructions to its transfer agent with respect to the Restricted
Stock, and that the certificates evidencing the Restricted Stock will contain a
standard legend to the effect that the shares of Restricted Stock are
"restricted securities" under the Act, and a legend in a form substantially as
follows:

        "The stock represented by this certificate is subject to limitations on
        transfer set forth in an agreement dated as of __________ ___, 2002,
        between the Company and the holder of such stock."




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On Assignment agrees that in connection with any permitted sales of Restricted
Stock under this Agreement pursuant to Rule 144, it will take all necessary
actions to remove such legends and withdraw such stop transfer instructions to
effect such sales.

        3. The undersigned hereby confirms his understanding that his execution
of this letter was a condition precedent to the completion of the Merger and
that On Assignment will rely upon his representations and agreements set forth
herein. The provisions of this letter shall be binding on the undersigned and
his successors, heirs, personal representatives and permitted transferees.

        4. This letter shall be governed, construed and enforced in accordance
with the laws of the State of California as applied to contracts without giving
effect to principles of conflicts of laws.

        5. Any action or proceeding seeking to enforce any provision of, or
based on any right arising out of, this Agreement shall be brought against any
of the parties hereto in any Federal or state court located in the State of
Delaware, and each party hereto consents to the jurisdiction of any such court
(and of the appropriate appellate courts) in any such action or proceeding and
waives any objection to venue laid therein. Process in any action or proceeding
referred to in the preceding sentence may be served on any party anywhere in the
world.



                                                Very truly yours,



                                                ----------------------------
                                                J. William Deville

AGREED:

ON ASSIGNMENT, INC.



By:
   ---------------------------------
   Dr. Joe Peterson
   Chief Executive Officer

Dated:  April ___, 2002



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