AbstractA geronto‐psychiatric epidemiological study was carried out in Kanagawa prefecture. The total sample comprised 1800 subjects randomly selected among 224 492 people aged 65 years and over. Two hundred and thirty subjects with suspected ill health, selected from the primary survey by lay raters, were individually interviewed to perform psychiatric and physical evaluations by psychiatrists and psychologists with a semi‐structured interview form. Strict criteria similar to that of DSM‐III were used to diagnose dementia. The study revealed that the prevalence of the aged with dementia in the community was 4.8%. Prevalence increased with age and showed a great predominance of vascular dementia. The prevalence of non‐vascular senile dementia in Japan is lower than that reported in studies from outside Japan. Some possible explanatory factors for this finding are di