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                                                                     EXHIBIT 4.3

                AMENDMENT NO. 1 TO THE RIGHTS AGREEMENT BETWEEN
                               ADMINISTAFF, INC.
                                      AND
                 HARRIS TRUST AND SAVINGS BANK, AS RIGHTS AGENT


                  THIS AMENDMENT NO. 1 ("Amendment No. 1") to the Rights
Agreement, dated as of February 4, 1998 (the "Rights Agreement"), is by and
between Administaff, Inc., a Delaware corporation (the "Company"), and Harris
Trust and Savings Bank, as Rights Agent (the "Rights Agent"). This Amendment
No. 1 is dated as of March 9, 1998. Capitalized terms used herein but not
defined shall have the meanings assigned to such terms in the Rights Agreement.

                                R E C I T A L S:


                  WHEREAS, the Company and the Rights Agent have heretofore
executed the Rights Agreement; and

                  WHEREAS, the Company desires to amend the Rights Agreement to
revise clause (iii) of the definition of "Exempt Person" included in Section
1(p) thereof; and

                  WHEREAS, in accordance with Section 27 of the Rights
Agreement the Rights Agreement may be amended without the approval of any
holders of Rights;

                  NOW, THEREFORE, in consideration of the premises and the
mutual agreements herein set forth and in accordance with Section 27 of the
Rights Agreement, the parties hereby agree as follows:

                  1. Clause (iii) of the definition of "Exempt Person" included
         in Section 1(p) of the Rights Agreement is hereby amended, effective
         as of the date set forth above, by revising such clause (iii) to read
         in its entirety as follows:

                           "(iii) American Express Travel Related Services
                           Company ("AXTRSC"), its Affiliates and Associates
                           (provided that, for purposes of this sub-clause
                           (iii) only, the terms Affiliate and Associate as
                           used with respect to AXTRSC shall not include
                           nonemployee directors of AXTRSC or its affiliates
                           that are in the investment advisory, discretionary
                           money management, asset management, brokerage,
                           insurance, annuity, lending or similar business to
                           the extent such non-employee directors are acting
                           for their own account or for the account of, or
                           investing the funds of, their respective customers
                           or clients or funds advised or distributed by



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                           them) (collectively, the "AMEX Stockholders"),
                           provided that the AMEX Stockholders shall cease to
                           be an Exempt Person if the shares of which the AMEX
                           Stockholders are the Beneficial Owner exceed 19.9%
                           of the Common Stock determined on a Fully Diluted
                           Basis at the time of calculation (the "AMEX
                           Threshold"); provided, however, that (A) if during
                           the term of this Agreement the AMEX Stockholders
                           sell, transfer or otherwise dispose of any shares of
                           Common Stock of which the AMEX Stockholders are a
                           Beneficial Owner and after giving effect to (and
                           solely as a result of) such sale(s), transfer(s) or
                           disposition(s) the AMEX Stockholders Beneficially
                           Own less than 15.8% of the Common Stock on a Fully
                           Diluted Basis, the AMEX Threshold shall be reduced
                           to that percentage of the Common Stock of which the
                           AMEX Stockholders are a Beneficial Owner, determined
                           on a Fully Diluted Basis immediately after giving
                           effect to such sale, transfer or other disposition
                           (assuming for purposes of such calculation that
                           after giving effect to the closing of the
                           transactions contemplated by the Securities Purchase
                           Agreement, dated as of January 27, 1998, as amended
                           ("AMEX Investment Agreement"), among the Company,
                           its subsidiaries and AXTRSC the AMEX Stockholders
                           were the Beneficial Owner of 19.9% of the Common
                           Stock determined on a Fully Diluted Basis), and (B)
                           if the AMEX Threshold is reduced during the term of
                           this Agreement to 15% or less, then the AMEX
                           Threshold shall be 15%. As used in clause (iii) of
                           this definition, the term "Fully Diluted Basis"
                           means the sum, without duplication, of (i) all
                           shares of Common Stock then outstanding (as such
                           term is used in the definition of Beneficial
                           Ownership in Section 1(d) hereof), (ii) shares of
                           Common Stock issuable upon the exercise of all
                           outstanding warrants, options and other rights to
                           acquire Common Stock, directly or indirectly, and
                           (iii) Common Stock issuable upon conversion of all
                           securities convertible, directly or indirectly, into
                           Common Stock."

                  2.       Except to the extent amended by this Amendment No. 1,
                           the Rights Agreement shall continue in full force and
                           effect.


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

                                        ADMINISTAFF, INC.


                                        By:  /s/ Paul J. Sarvadi
                                             ----------------------------------
                                             Name:  Paul J. Sarvadi
                                             Title: President and
                                                    Chief Executive Officer


                                        HARRIS TRUST AND SAVINGS BANK,
                                             as Rights Agent


                                        By:  /s/ Lorraine Rodewald
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                                             Name:  Lorraine Rodewald
                                             Title: Assistant Vice President