The prevalence of diabetes mellitus in the traditional-living population of Wallis Island was low and comparable with that found in other rural Polynesian societies. The diabetes prevalence was 1.9% in men and 3.5% in women; impaired glucose tolerance occurred in 5.0% of men and 8.4% of women. The prevalence of obesity was significantly greater in women than in men (37.4% versus 12%, respectively, were equal to or greater than 140% ideal weight). Subjects with diabetes tended to be more obese and less active than normal subjects, but these differences, although appreciable, were not usually statistically significant. The population engages in considerable physical activity, and this, along with the traditional diet, may be responsible for the relatively low diabetes prevalence.