Recent studies have suggested that the renin-angiotensin system is a feature of the insulin resistance syndrome. However, whether such a relationship occurs in childhood and in both African Americans and whites is not clear. We examined this issue in a sample of 264 African American and white children aged 7 to 16 years who participated in a cross-sectional survey of the Bogalusa Heart Study (n = 3,524). Children were selected using a stratified random sampling procedure based on race-, age-, and sex-specific percentiles of diastolic blood pressure. Whites had higher plasma renin activity than African Americans (7.1 +/- 3.6 ng/mL/h v 5.3 +/- 3.5 ng/mL/h, P < .01). Renin activity correlated with blood pressure (BP) (r = 0.21, P < .05) and insulin resistance index defined by post-glucose 1-h insulin X 1-h glucose (r = 0.19, P < .05) only in white children. Other components of insulin resistance syndrome (percent body fat, systolic blood pressure, high-density lipoprotein cholesterol, and triglycerides) showed no relation to renin in both races using univariate analyses. The distribution of insulin resistance index and renin activity among children with elevated BP (above 90th percentile) showed that the percentage of children with both high insulin resistance index and renin values was significantly greater in whites than in African Americans (45.6% v 23.3%, P < .05). A multivariate factor analysis of risk variables of insulin resistance syndrome resulted in clusters of BP/adiposity (factor 1), lipids/adiposity (factor 2), and insulin resistance/renin/adiposity (factor 3) in white children, with adiposity linking the three factors. However, a different pattern emerged in African American children for factor 2 and factor 3, and renin was not part of the cluster in any of the three factors. These observations suggest that renin may be a component of insulin resistance syndrome detectable in early life only in whites.