The benefits and potential risks of estrogen use in post menopausal women were discussed at the 61st Annual Meeting of the Endocrine Society. The proven benefits of estrogen treatment include: 1) relief of symptoms such as hot flashes and atrophic changes in the vagina and breast due to a postmenopausal decrease in estrogen; and 2) a diminution of the degree of menapausal osteoporosis, a major health problem in aged 65 and older. Studies have shown a consistant improvement in the maintenance of skeletal mass when estrogen therapy is given. Adverse reactions to estrogen include an increase hepatic secretion of renin substrate resulting in increased blood pressure. Also, studies show both an increased coagulability of blood and cholesterol supersaturation of bile. Prime concern to women treated with the hormone therapy is the two to eight fold increase in risk of developing uterine cancer which increases with duration of estrogen use. Estrogen, although itself not a carcinogen appears to maintain the uterus in a condition that allows it to more readily respond to a carcinogenic stimuli. The relationship of estrogen use to lipoprotein metabolism and coronary heart disease is yet another area to be further studied.