Osteoporosis is a bone disorder characterized by deficient bone mass and fragility fractures of the hip, wrist, and spine. The therapeutic strategies for treating osteoporosis are designed to maximize peak bone mass through proper nutrition, appropriate intake of calcium and vitamin D, maintenance of physiologic menstrual cycles, and a program of weight bearing and strengthening exercises. For the conditions of high bone turn-over- osteoporosis in which osteoclastic resorption is increased- efficacious treatment options include hormone replacement therapy, calcitonin, and bisphosphonates. Osteoporosis with low bone turnover results from deficient osteoblastic bone formation and responds to the experimental drug programs of fluoride, parathyroid hormone, and parathyroid hormone related peptide analogues. Determination of bone density defines the patient's current condition, measurement of the level of N-telopeptides (collagen breakdown products) predicts the patient's future regarding osteoporotic fractures, and the presence of risk factors for hip fracture establish the therapeutic window for treatment.