A cross-sectional survey of diabetes, hypertension, obesity and dietary patterns has been conducted in the Western Province of the Solomon Islands. Three groups--traditional and more urbanized Melanesians and semitraditional Micronesians--were compared. Abnormal glucose tolerance was rare (less than 1% over all) in Melanesians regardless of acculturation, but was present in 9.7% of adult Micronesians in whom it was associated with age; obesity; female sex; and a diet that was high in energy and refined carbohydrates. Hypertension, which was associated with advancing age and obesity, was recorded in 6.0% and 8.3% of traditional and partly urbanized Melanesians, respectively, and in 4.8% of Micronesians. Systolic and diastolic blood pressures correlated significantly with age for all except traditional Melanesian women among whom the association was limited to the systolic blood pressure only. Significant correlation coefficients were recorded between diastolic blood pressure and body mass index for both sexes and all groups, and between systolic blood pressure and body mass index for all women but only for Micronesian men. Dramatic differences in life-style and dietary patterns are described for rural and more urbanized Melanesians among whom the mean daily urinary sodium outputs were 67 and 119 mmol/L, respectively.