Osteoporosis is perhaps the widest-ranging social, physical, and economic impact of estrogen deficiency. Postmenopausal bone loss is the major determinant of osteoporosis. Osteoporotic risk can be determined by measuring bone mineral density using dual X-ray absorptiometry. The radiation free quantitative bone ultrasound is emerging in the assessment of bone structure giving reliable estimates of fracture risk. Diet and exercise are important in determining a woman's risks for osteoporosis. Hormone replacement therapy clearly decreases bone turnover and prevents postmenopausal bone loss and reduces fractures. Tibolone as well as raloxifene prevent bone loss and solid data demonstrate a reduction of vertebral fractures after raloxifene administration.