Kuru is a fatal progressive disease of the central nervous system with clinical manifestations of ataxia, dementia, and myoclonus. So far, kuru and Creutzfeldt-Jakob disease (C-J) are the only two forms of transmissible subacute spongiform viral encephalopathy known to affect humans. All of the reported cases of kuru have occurred in a restricted area of New Guinea, while Creutzfeldt-Jakob has had a wide distribution. We have examined postmortem tissue from a 54-year-old Jamaican woman with an 11-month progressive ataxic and dementing illness, clinically diagnosed as the ataxic form of C-J. Light and electron microscopic examination of the brain showed the distribution and changes described in kuru, including the presence of numerous PAS-positive kuru plaques in the cerebellum.