This study examined risk factors for coronary disease and plasma triglycerides, total cholesterol, HDL, LDL cholesterol (C), Apo A-1, and Apo B lipoprotein levels in obese children (n = 107) aged 9-12 years old and in children (n = 64) hereditarily predisposed to coronary heart disease (CHD). In the latter group, children's fathers had a history of MI before 50 years of age. A control group of 30 children was also studied, and the plasma lipid profile was investigated in 35 fathers with premature myocardial infarction. Seventy-five percent of the obese children and 60% of the children hereditarily predisposed to CHD had three or more coronary artery disease risk factors. Plasma HDL-C (p < 0.001), LDL-C (p < 0.001-p < 0.05, respectively), Apo A-1 (p < 0.001), and Apo B (p < 0.001) levels were different in both groups compared with controls.