Gerstmann-Sträussler-Scheinker's disease is a familial spongiform encephalopathy whose pathological hallmark is the existence--especially in the cerebellum--of numerous amyloid plaques. We report here the third clinicopathological case in a French family. Brain tissue from one of its members--initially described as familial Creutzfeldt-Jakob's disease--has been reported as successfully inoculated to monkeys. We present the currently accumulating data favouring the hypothesis of a common etiology for familial Creutzfeldt-Jakob's disease and Gerstmann-Sträussler-Scheinker's disease. The familial characteristics, resulting in different durations of incubation and evolution, could lead to different clinical and histological expressions.