Osteoporosis is generally considered an age-related reduction in the quantity and quality of bone, but it need not be considered an inevitable consequence of aging. Primary prevention of osteoporosis is clearly desirable, and all women should receive counseling regarding universal preventive measures such as dietary calcium and vitamin D, weight-bearing and resistance exercises, and smoking cessation. Perimenopausal and postmenopausal women should also be counseled about the potential benefits and risks of hormone prophylaxis. For individuals who are unable to take estrogens, other pharmacologic measures are available for prevention. Osteoporosis may also affect elderly men and patients receiving glucocorticoid therapy, and preventive measures should also be used for them.