When used for the primary prevention of coronary heart disease in persons with heterozygous familial hypercholesterolemia (hFH), a hydroxymethylglutaryl coenzyme A (HMG CoA) reductase inhibitor is projected to be effective and to have very favorable cost-effectiveness ratios at low-to-medium doses. For example, 20 mg of lovastatin per day is estimated to save lives and save money in all men ages 35-44 years with hFH and in women ages 35-44 years with hFH and any other risk factor. The estimated incremental cost effectiveness of 40 mg compared with 20 mg of lovastatin for individuals with hFH ages 35-44 years was less than $45,000 per year of life saved in men with > or = 1 other risk factors and women with > or = 2 other risk factors. The estimated incremental cost-effectiveness ratio of 80 mg compared with 40 mg/day was substantially higher ($100,000 or more per year of life saved) even in the highest risk persons. The estimated cost-effectiveness ratios for primary prevention in hFH were reasonably similar to the favorable ratios for secondary prevention in the general population but substantially better than the estimated ratios for primary prevention in other adults with high cholesterol levels. Any national recommendations regarding the use of medications for individuals with hFH must include cost considerations. Our analyses support the use of low-to-moderate doses of high-cost medications for primary prevention in these patients.