Epistylis infections were found on 16 fish species in the Yadkin and Catawba River reservoirs in North Carolina during 1974-75. Families most affected were Ictaluridae, Percichthyidae, and Centrarchidae. Highest incidence of the disease occurred during the summer and fall months. The most common infection site among most species of fishes was inside the mouth. A positive correlation was found between total fish length and Epistylis infection rate among Lepomis auritus, Lepomis macrochirus, and Micropterus salmoides. The bacterium, Aeromonas hydrophila, often was isolated from Epistylisinfected fishes and was believed responsible for two large fish kills.