Eight hundred and eighty four autopsy brains from patients with clinically diagnosed Alzheimer's disease were examined pathologically. Six hundred ninety eitht(79.96%) of the 884 cases fullfilled histological criteria for Alzheimer's disease, with or withour additional fndings, such as substantia nigral degeneration, cerebellar degeneration, Parkinson's disease or cerebral infarcts. One hundred and eighty six cases(20.04%) were diagnosed as other neurodegenerative disease such as Parkinson's disease, non-specific cortical degeneration or Pick's disease. Degenerative changes in the substantia nigra were common in patients with Alzheimer's disease than has been reported for the general aged population. Brain atrophy was severer in presenile type of Alzheimer's disease than in senile type of Alzheimer's disease.