Women are being presented with an increasing number of choices for health care management as they move through the aging process. Estrogen has positive effects on mood, sexual function, target end organs and cognitive function, and may play an important role in the etiology of Alzheimer's Disease by acting to prevent amyloid plaque formation, oxidative stress, or deterioration of the cholinergic neurotransmitter system. The benefits of estrogen therapy for osteoporosis, the cardiovascular system, and lipid metabolism are far reaching, but the possibility of developing breast cancer later in life is also relevant. Understanding the mechanisms for the action of the estrogens, anti-estrogens, and the selective estrogen receptor modulators, and possible alternative routes of symptom management for some menopausal events is important to make appropriate decisions on choice of therapy. This review discusses the theoretical basis for estrogen's actions in the management of the postmenopausal stage of the life cycle.