To explore the relationship between the body mass index (BMI) and uric acid in different races before growing up into adulthood, we selected a total of 1236 five to 14 year-old children in the period from March to December 1994. The children originated from three Aboriginal tribes (the Bunun, and the Paiwan tribes--classified as South-Aborigines and Atayal tribe as North-Aborigines) and two non-Aboriginal tribes (Fukein-Taiwanese and Hakka), all of whom are from the following four countries: Chien-Shih, Sandimen, Gaushuh and Sanmin. The results showed that the percentage of hyperuricemia (> or = 7.5 mg/dl) was 28.5% (352/1236) and of obesity (BMI > or = 22 kg/m2) was 9.5% (118/1236). Increased uric acid concentration was found to be related to age, sex, BMI, race, triglyceride (TG) and cholesterol levels in both the primary analysis and after the adjusted logistic regression model. Obesity did not vary with sex (OR = 1.0; 95% CI = 0.7-1.5), or with Aborigines in north Taiwan as compared with non-Aborigines (OR = 1.0, 95% CI = 0.6-1.6), but the logistic regression model adjusted for age indicated large BMI values for children with high serum uric acid concentration, triglyceride levels and the Aborigines who originated from south Taiwan. It was concluded from this study that both of the North-Aborigines and South-Aborigines made an important influence on serum uric acid concentration in children, especially the South-Aborigines made difference to BMI as compared with non-Aborigines and North-Aborigines.