A survey to investigate the psychiatric and physical characteristics of centenarians was conducted from 1987 to 1989 in the Tokyo metropolitan area with a team of psychiatrists and psychologists using a semi-structured interview form. In that 3-three period, out of 509 centenarians living in Tokyo, 294 persons and their caregivers (57.8%) including the 65 institutionalized centenarians were examined. Two hundred and fifteen centenarians were not able to be interviewed due to various reasons. Out of 294 centenarians, 76 persons (25.9%) were interviewed by telephone. Also out of these, 176 (59.8%) were living with their son's or daughter's family. Ten male centenarians (12.8%) were living with their wives, while no female was living with a spouse. Five men and four women were living alone. There was a marked difference of education in years between both sexes. Mean years of education were 10.2 in the male and 5.5 in the female. According to the Clinical Dementia Rating, 31.6% out of 218 centenarians interviewed were not demented and those with dementia were even distribution of mild, moderate and severe dementia. There were marked differences according to sex, similar to that found in ADL. Of 63 males, 46.0% were not demented, whereas 25.8% of 155 females were not demented. Only 3.2% of males were severely demented, but in females 27.1% showed severe dementia. HDS scores decreased in relation to the advance in severity of dementia. Approximately 27% of the cases had no previous physical histories; 21.8% for the male and 29.2% for the female.(ABSTRACT TRUNCATED AT 250 WORDS)