Dietary data was obtained from 77 adult Micronesian (Nauruan) subjects during a diabetes epidemiological survey. The life-style of this isolated Pacific population is almost completely Westernized and they have been shown to have a very high diabetes prevalence rate. Nearly all food consumed by the islanders is imported from Australia. The main caloric intake of both males and females was at least twice those recommended for Western or developing Pacific populations. The diet meets or exceeds the Australian National Health and Medical Research Council recommended allowance for calories, protein, fat, and ascorbic acid, but thiamin intake was inadequate. The percentage of fat in the diet was lower than that consumed by Western populations. Obesity is a pronounced feature of this population and the high caloric intake coupled with reduced physical activity would appear to be a major factor in relation to this. The Micronesian group has a genetic susceptibility to diabetes which may have been unmasked by the change from traditional to Western life-style. This problem may not be unique to Nauru and, with progressive Westernization, many other Polynesian and Micronesian populations may be at risk.