The patterns of disease among the Japanese who migrated to Hawaii differ from those among indigenous Japanese and among Japanese who migrated to the continental United States. They have the highest mean age at death (77 years in 1970) of any of the races in Hawaii. Review of autopsies performed on 1,376 Hawaiian Japanese 65 years of age or older indicated that many of these subjects had cancers that were not suspected clinically. The highest incidence of such previously unsuspected tumors was found among the oldest subjects--the age group with the lowest percentage of autopsies in the state--indicating that this analysis understates the real frequency of such tumors in persons in these age groups. The tumor site of the largest proportion of clinically undiagnosed carcinomas was the liver--ten of 23 cases (43 per cent). Autopsy diagnoses of gastric cancer were made in 29 of the 142 carcinomas (21 per cent) that had developed at this site. All but three of the unsuspected gastric tumors were asymptomatic, and 73 per cent of the asymptomatic tumors were stage I. Among 93 colorectal carcinomas, 28 (30 per cent) were diagnosed at autopsy, and 75 per cent of the 20 occult asymptomatic tumors at this site were Duke's stage A.