Atherosclerosis is a process that begins in early life. Coronary heart disease is the result of complex interactions among a variety of risk factors of which hypercholesterolemia is but one. During routine screening, 500 children were identified with total cholesterol levels above the 95th percentile of 5.2 mmol/L (200 mg/dL). Lipoprotein profiles were then performed to confirm and delineate their lipid abnormalities. A definable lipid disorder was present in 85% of such children. Abnormal lipoprotein patterns included 292 children with type IIa, 99 with type IIb, and 25 with type IV phenotypes. An abnormally low high-density lipoprotein cholesterol level of less than 0.9 mmol/L (35 mg/dL) was observed in 20 children. Only 5% of patients were identified as being hypercholesterolemic because they had high-density lipoprotein cholesterol levels above the 95th percentile of 1.8 mmol/L (70 mg/dL). Thirty-two percent of children with total cholesterol levels above 5.2 mmol/L had a family member (sibling, parent, uncle, aunt, or grandparent) with a myocardial infarction prior to 55 years of age. Data from this study support universal cholesterol testing after 3 years of age and lipoprotein profiles for those with levels above 5.2 mmol/L.