Heterozygous familial hypercholesterolemia (HeFH) is associated with elevated cholesterol levels and early-onset atherosclerosis. We assessed the efficacy and safety for up to 2 yr of pravastatin treatment in 19 girls and 11 boys (age range, 4.1-18.5 yr) with HeFH. Pravastatin was started at 10 mg/d, with a forced titration by 10 mg at 2, 4, 6, and 12 months until the target cholesterol level [< or =194 mg/dl (< or =5 mmol/liter)] was reached. By 2, 4, 6, 12, and 24 months of treatment, the total cholesterol levels had, respectively, decreased by 19, 20, 23, 27, and 26%, and the low-density lipoprotein cholesterol levels had decreased by 25, 27, 29, 33, and 32% compared with the dietary baseline values. Seventeen percent of patients had lipid deposits (carotid plaque, xanthomas, or corneal arcus) at baseline, and 27% had deposits at 1 yr. The side effects were mild, and no clinically significant elevations in alanine aminotransferase, creatine kinase, or creatinine were seen. Growth and pubertal maturation remained normal in all subjects. In conclusion, pravastatin treatment was safe and well tolerated. The efficacy in children with slight or moderate hypercholesterolemia was satisfactory, but in children with severe hypercholesterolemia, it was insufficient.