High blood cholesterol in childhood associated with early development of atherosclerotic plaques has been well established. To find the prevalence of hyperlipidemia in children at risk for coronary heart disease, the authors performed cholesterol screening in children aged between 5-18 years from families with a history of premature coronary heart disease and/or parental hypercholesterolemia. All children were measured for non-fasting capillary blood total cholesterol level by Reflotron dry chemistry method, and lipoprotein analysis was done in children whose capillary blood cholesterol level was > or = 170 mg/dl. One hundred and sixty-five children participated in this study. Eighty-seven (52.7%) of the total had a non-fasting capillary blood cholesterol level > or = 170 mg/dl, and 75 (87.2%) of these children were measured for lipoprotein analysis. Total cholesterol level > or = 200 mg/dl, low density lipoprotein cholesterol (LDL-C) > or = 130 mg/dl, and high density lipoprotein cholesterol (HDL-C) < 35 mg/dl were found in 43 (57.3%), 50 (66.7%) and 9 (12.0%) children respectively. As a result of this study, Thai children at risk for coronary heart disease had a high prevalence of abnormal lipid profile, which may predict the high prevalence of premature coronary heart disease in the future.