OBJECTIVE To assess differences in body composition between Polynesians and Caucasians subjects. METHODS 48 male and 80 female Polynesians from a village in Rarotonga, Cook islands (81% response rate) and representative sample of 243 male and 250 female Caucasians from Melbourne, Australia. METHODS Body mass index, resistance from bioelectrical impedance, percent body fat derived from 4 equations using resistance, weight, height, age and sex. RESULTS Male and female Polynesians were younger (by 7.7 years, P < 0.001 and 4.1 years, P < 0.05) and heavier (by 10.7 kg and 12.5 kg, P < 0.0001) than their Caucasian counterparts. Electrical resistance was significantly lower in Polynesians of both sexes by over 130 omega (P < 0.0001). At every level of weight (adjusted for height and age), resistance was lower in the Polynesians (P < 0.0001) and at every level of body mass index, the predicted body fat from 4 different equations was lower in Polynesians (P < 0.0001). CONCLUSIONS These results imply that, at any given body size. Polynesians are significantly leaner than Caucasians and that specific Polynesian standards for defining obesity need to be developed. The findings will need to be confirmed by other reference methods for measuring body composition.