Cerebral amyloid angiopathy is observed in several brain degenerative disorders, but this pathological condition has received little attention in Gerstmann-Sträussler-Scheinker disease (GSS). We report a 69-year-old man who showed the cardinal features of GSS together with typical and extensive congophilic angiopathy. Immunohistochemical studies revealed that the vast majority of the amyloid plaques present in the brain of this patient were consistently labeled by anti-prion protein (PrP) antibody. Double immunostaining disclosed many additional beta-protein immunoreactive plaque-like lesions, including a special type of "hybrid" plaque with colocalization of PrP and beta-protein (beta-PrP). The vascular amyloid deposits seen in both the cerebellum and cerebrum were immunoreactive only to anti-beta-protein antibody. It seems likely that the extensive deposition of beta-protein amyloid (including brain vascular amyloidosis) seen in this and other similar cases is part of pathology of GSS, although the possibility that this finding is due to ageing or concomitant Alzheimer's disease cannot be completely ruled out.