In this epidemiological study of physical and mental health of very old Palauans, all residents of Palau over 90 years of age were interviewed in their places of residence. All 31 subjects lived with relatives or a spouse in widely scattered small villages on three main islands, but the majority were in Koror, the largest population centre. The proportion of the total population over 90 years of age was approximately that in the US: 0.2% versus 0.3%. However, there was a large number of centenarians, 1/2000. The prevalence of dementia as determined by clinical assessment was high: 25% mild and 42% moderate or severe. This prevalence was lower (44%) as determined by the Global Deterioration Scale. Physical illness and functional mental illness were infrequent low but most subjects had at least one chronic illness, the most common being arthritis. Most chewed betel nut. Few used alcohol or smoked. An adaptation of the Wechsler logical memory test and the Global Deterioration Scale appeared to be useful in assessing cognitive function in this non-Western culture.