A case-control study was performed by the Research Center of Isfahan University, to determine the predisposing factors of early atherosclerosis. Children of cases admitted to a university hospital in Isfahan with early myocardial infarction (MI) were considered for the study. The affeckted cases (n=116), had 120 children aged 2-14 years. The control group were selected from children of the neighbors of the cases. The two groups were similar in age of parents, children and socio-economic status. Mean cholesterol and triglyceride levels and the frequency of hypercholesterolemia and hypertriglyceridemia were significantly higher in the children of MI cases. The mean lipid concentration of the controls was significantly higher than standard levels. These results emphasize the importance of evaluating children of high risk cases for risk factors of MI.