In women, serum lipid levels and the incidence of myocardial ischemia increase after menopause. Deficiency of estrogen is believed to be the cause of these epidemiological phenomena. On the other hand, hormone replacement therapy(HRT), has prevailed in developed countries. Estrogen is replaced to ease climacteric disorders, and retard bone loss. Many clinical studies cleared the effect of HRT on lipids, in which total and LDL-C (cholesterol) decreased, and HDL-C increased. TG increased by conjugated equilin estrogen but not by transdermal estradiol. In our study, hepatic triglyceride lipase(HTGL) was suppressed by HRT, but lipoprotein lipase(LpL) was not suppressed. HRT decreases coronary artery diseases, but it is still controversial whether HRT is efficient in patients who already have heart disease.