Dreyfus Government Cash Management Funds - Definitive materials filed by investment companies. (497)

May 8, 2008

DREYFUS CASH MANAGEMENT DREYFUS CASH MANAGEMENT PLUS, INC. DREYFUS GOVERNMENT CASH MANAGEMENT DREYFUS GOVERNMENT PRIME CASH MANAGEMENT DREYFUS MUNICIPAL CASH MANAGEMENT PLUS DREYFUS CALIFORNIA AMT-FREE MUNICIPAL CASH MANAGEMENT DREYFUS NEW YORK AMT-FREE MUNICIPAL CASH MANAGEMENT DREYFUS NEW YORK MUNICIPAL CASH MANAGEMENT DREYFUS TAX EXEMPT CASH MANAGEMENT DREYFUS TREASURY & AGENCY CASH MANAGEMENT DREYFUS TREASURY PRIME CASH MANAGEMENT

Supplement to Combined Statement of Additional Information dated March 31, 2008

      Dreyfus New York AMT-Free Municipal Cash Management (the “NY AMT-Free Fund”) currently is not offered to investors. This Combined Statement of Additional Information, as it relates to the NY AMT-Free Fund, is to be used only in connection with the Combined Prospectus/Proxy Statement sent to shareholders of BNY Hamilton New York AMT-Free Municipal Money Fund, a series of BNY Hamilton Funds, Inc., in respect of the proposed reorganization of that fund.

      The following information supersedes and replaces any contrary information contained in the Combined Statement of Additional Information.

      Each fund will disclose daily, on www.dreyfus.com , the fund’s complete schedule of holdings as of the end of the previous business day. The schedule of holdings will remain on the website until the fund files its Form N-Q or Form N-CSR for the period that includes the date of the posted holdings.

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