The histopathology of fin rot disease in winter flounder, Pseudopleuronectes americanus, from the New York Bight is described. Fin rot in winter flounder was characterized by progressive loss of portions of the anal and dorsal fins. Microscopic findings included epidermal hyperplasia accompanied by dermal fibrosis, hyperemia, and hemorrhage. Bacteria were not observed in situ and a pronounced leukocytic inflammatory response was not noted.