X0101 EFFECT 33 LIVE 2008-03-31 15:30:00

N-1A

0001423799 Dreyfus Institutional Reserves Funds 333-148652 S000021488 Dreyfus Institutional Reserves Money Fund C000061453 Institutional Shares S000021488 Dreyfus Institutional Reserves Money Fund C000061454 Hamilton Shares S000021488 Dreyfus Institutional Reserves Money Fund C000061455 Agency Shares S000021488 Dreyfus Institutional Reserves Money Fund C000061456 Premier Shares S000021488 Dreyfus Institutional Reserves Money Fund C000061457 Classic Shares S000021489 Dreyfus Institutional Reserves Government Fund C000061458 Institutional Shares S000021489 Dreyfus Institutional Reserves Government Fund C000061459 Hamilton Shares S000021489 Dreyfus Institutional Reserves Government Fund C000061460 Agency Shares S000021489 Dreyfus Institutional Reserves Government Fund C000061461 Premier Shares S000021490 Dreyfus Institutional Reserves Treasury Fund C000061462 Institutional Shares S000021490 Dreyfus Institutional Reserves Treasury Fund C000061463 Hamilton Shares S000021490 Dreyfus Institutional Reserves Treasury Fund C000061464 Agency Shares S000021490 Dreyfus Institutional Reserves Treasury Fund C000061465 Premier Shares S000021490 Dreyfus Institutional Reserves Treasury Fund C000061466 Classic Shares S000021491 Dreyfus Institutional Reserves Treasury Prime Fund C000061467 Institutional Shares S000021491 Dreyfus Institutional Reserves Treasury Prime Fund C000061468 Hamilton Shares S000021491 Dreyfus Institutional Reserves Treasury Prime Fund C000061469 Agency Shares S000021491 Dreyfus Institutional Reserves Treasury Prime Fund C000061470 Premier Shares