A disfiguring shell disease was detected in river cooters (Pseudemys concinna) and yellow-bellied turtles (Trachemys scripta) from Lake Blackshear, Georgia (USA). The turtles used were part of a mark-recapture study conducted from September 1991 to June 1993. Histologic changes on four turtles included acute segmental necrosis of the epidermis, followed by ulceration, necrosis of the underlying dermis and dermal bone, and exaggerated remodeling of bone. Additional findings included visceral inflammatory lesions and bacterial infection, sepsis, and marked trematode ova granulomatosis. The cause of the shell lesions was not determined.