The prevalence of dementing disorders in Campo Grande of a community of Japanese‐Brazilians who immigrated from Okinawa was studied. Previous reports showed that the dietary pattern in Japanese immigrants in Brazil, which characterized by a low fish and large meat intake, is possibly responsible for increased risk of cardiovascular diseases compared with Japanese in Okinawa. A total of 157 persons over 70‐year‐old were examined, and 19 cases were diagnosed as having dementia. The prevalence (cases/100 aged 70‐year‐older) was 12.1 for all types of dementia, 5.7 for Alzheimer's disease (AD), 0.6 for vascular dementia (VD), 4.5 for mixed dementia (AD/VD) and 1.3 for other types of dementia. There was no case of dementia with Lewy bodies or frontotemporal lobar degeneration. These results are similar to many previous studies in Western countries and some recent surveys in Japan, and clearly show that more AD than VD appears even in the Japanese‐Brazilian population. The higher prevalence rate of dementia in Japanese‐Brazilians compared with several studies in Japan may indicate the importance of dietary factors rather than genetic factors.