Women are about 10 years older than men to suffer from ischemic heart disease(IHD) and they often experience a sudden rise in cholesterol after menopause. These phenomena are thought to be caused by the production of estrogen in women during normal menstruation cycle and its loss after menopause. Hormone replacement therapy(HRT) has been shown to reduce IHD by nearly 50 per cent. This is caused in part by effects of estrogen on lipid metabolism; it reduces LDL and Lp(a), and increases HDL. Although the first large prospective trial of HRT for secondary prevention of IHD failed to demonstrate estrogen's protective effects, HRT was effective in women with high Lp(a). Thus, selection of patients and HRT regimen seems important.