Nearly one-half of an American woman's life is spent after the cessation of reproductive function. A woman of 40 years has an additional life expectancy of nearly 40 years; a woman of 75, over 11 years. This pattern of longevity is likely to continue, so that by the year 2000, it has been estimated, 30 percent of the female population will be postmenopausal. While it is difficult to separate the results of aging from those of estrogen deprivation, it is important that we try to do so, since the results of the latter are amenable to treatment. The medical infirmities resulting from estrogen deprivation take a high toll among postmenopausal women. Nearly 200,000 hip fractures occur annually in this group, resulting in 15,000 deaths and a high morbidity rate. Sleep disorders, compromised sexuality, psychomotor alterations of the climacterium, and urinary tract disorders all contribute to a lowered quality of life. Appropriate treatment of these disturbing postmenopausal conditions requires an understanding of the underlying bio­ chemical, endocrinologic, psychologic, and pathophysiologic al­ terations of estrogen deprivation. Toward this end, the reader will find herein chapters dealing with estrogen metabolism in the postmenopausal female, end-organ response to estrogen deprivation, and bone metabolism and osteoporosis. Next, the reader will find chapters dealing with specific or­ gans, organ systems, or conditions related to the quality of life; for example, sexuality, urinary tract problems, sleep disorders, the breast, sports and exercise, the climacteric, and the psycho­ biology of the menopause.