The authors assessed the 3-year incidence of dementia, including subtypes, in 2,603 Japanese-American men 71 to 93 years of age who were dementia free at baseline. There were 137 new cases of dementia according to the Diagnostic and Statistical Manual of Mental Disorders, 3rd edition, revised, including 51 with a primary diagnosis of AD. The rates for all subtypes increased with age. Men with an APOE4 allele had a significantly increased risk of AD of 2.39 (95% CI, 1.07, 5.31), after adjusting for age and education. There was no significant relationship of APOE4 with other subtypes of dementia.