The purpose of this study was to examine coronary risk factors and physical activity patterns of primary and secondary school children in Singapore. Children 6-18 yr (730 boys, 849 girls) were evaluated for anthropometry, percent body fat, resting blood pressure, fasting plasma lipids and lipoproteins and glucose. A physical activity and leisure pursuits self-reported survey was used to group children into five categories ranging from "inactive" to "vigorous" activity. The self-reported questionnaire also recorded individual responses to exercise behaviors, leisure activities, and participation in organized games and sports. Body weight, body mass index (BMI; kg x m[-2]), and percent body fat were compared by age and gender. The blood analysis showed no significant differences in boys' and girls' plasma lipid and lipoprotein concentrations. Physical activity was significantly correlated with total cholesterol (rs = -0.13, P = 0.018) and triglycerides (rs = -0.18, P = 0.001) for boys and between physical activity with body fat (rs = -0.22, P = 0.0001) and BMI (rs = -0.16, P = 0.01) for girls. Height, weight, BMI, percent body fat, and blood pressure were greater for each age to 14 yr, after which there was less recorded body fat for boys. Girls' body fat remained about the same after 14 yr. Comparing by gender and age, significant differences were found between physical activity groups and total cholesterol and body fat. Although few children were at risk for heart disease, this study provides baseline coronary risk and physical activity data for further longitudinal analysis in this population.