Estimates from the Lipid Research Clinics Program indicate estrogen use in approximately one third of postmenopausal women. Analysis of Lipid Research Clinics data confirmed that administration of estrogens results in lower plasma low density lipoprotein levels and elevated plasma high density lipoprotein levels. Thus, the ratio of high density lipoprotein/low density lipoprotein levels is substantially increased. Given the inverse relationship between high density lipoprotein levels and coronary heart disease risk, this effect of estrogens on the plasma lipoproteins could be expected to further reduce coronary heart disease risk in women.