To analyze aggregation of risk factors for coronary artery disease (CAD), the authors studied 4538 children from the biracial community of Bogalusa, Louisiana. Of these children ranging in age from two to 18 years, 2535 had at least one sibling, permitting the calculation of F-ratios and intraclass correlation coefficients. Those calculations revealed statistically signigicant F-ratios for all anthropometric, blood pressure and lipid variables studied. Of the lipoprotein variables studied only alpha-lipoprotein showed no statistically significant aggregation (for black children). The analysis failed to reveal any significant differences in intraclass correlations between black and white children.