The Allegheny River drainage in southwestern New York supports a diverse fish fauna that i ncludes reports of 95 species. Of these, nine species are classified as endangered, threatened, or of special concern in New York; this number represents 38\% of the listed species in the state. Thirteen of the 95 species are reported only from the Allegheny River drainage and have not been found in other New York drainages. Eleven species are introduced, and four may have migrated into the drainage recently. Individual waters with high species richness, 46-67 species, include the Allegheny River, French Creek, Olean Creek, and Chautauqua Lake. The ichthyofauna of the Allegheny River drainage is important because of the number of rare fish species present in the drainage (26) when compared to other New York drainages.