Abstract:A neuropathologic study, chiefly cerebrovascular lesions and degenerative changes, was conducted on the brains of 233 subjects 50 years of age and over among 557 autopsy cases of RERF‐ABCC Hiroshima in 1972–1974. There were some discrepancies between the principal clinical diagnosis and principal pathologic diagnosis in cerebrovascular disease. For cerebral hemorrhage, 8.6% were accounted for in the clinical diagnosis of the entire subjects while only 2.1% were accounted for in the pathologic diagnosis of the same subjects. The degenerative changes in the central nervous system have been increasing with age and these changes were seen more in the females than in the males. Intracerebral arteriosclerosis of a moderate extension or more existed in 36.5% of the subjects and the frequency of this disease increased with age. The frequency of cerebral infarct increased with age. The location of the infarcts was most often seen in the basal ganglia and cortex of cerebrum, the size of the cortical infarct was within 0.5 cm in diameter and multiple. The vascular lesions or degenerative changes were seen in about 74% of the brains of 50 years and o