A total of 173 species of mayflies, representing 15 families and 45 genera, are reported from the state of New York. First state records for 43 species and 891 new county reports for 129 species are included. Previously published reports are summarized, and pertinent remarks on species are annotated. The occurrence of Dannella provonshai, Heptagenia julia, and Plauditus gloveri in New York represent significant range extensions. The discovery of Epeorus frisoni in New York represents only the second report of the species. Species potentially of environmental concern are noted.