EXHIBIT 99.3 [LETTERHEAD OF SALOMON SMITH BARNEY INC.] The Board of Directors Olsten Corporation 175 Broad Hollow Road Melville, New York 11747 Members of the Board: We hereby consent to the inclusion of our opinion letter dated August 17, 1999 as Appendix D-2 to, and to the reference thereto under the caption "THE TRANSACTIONS -- Opinion of Olsten's Financial Advisors" in, the Proxy Statement/Prospectus of Olsten Corporation ("Olsten") and Adecco SA ("Adecco") relating to the proposed merger transaction involving Olsten and Adecco, which Proxy Statement/Prospectus is part of the Registration Statement on Form F-4 of Adecco and on Form S-4 of Olsten Health Services Holding Corp. By giving such consent, we do not thereby admit that we are experts with respect to any part of such Registration Statement within the meaning of the term "expert" as used in, or that we come within the category of persons whose consent is required under, the Securities Act of 1933, as amended, or the rules and regulations of the Securities and Exchange Commission promulgated thereunder. By /s/ Salomon Smith Barney Inc. -------------------------------- SALOMON SMITH BARNEY INC. New York, New York October 7, 1999