Important secondary causes of osteoporosis which may be missed include primary hyperparathyroidism and hyperthyroidism, either of which may decrease bone density by 10–20%, and these conditions and others should be sought from the medical history, physical examination, and appropriate investigation. Estrogen therapy is a commonly used prophylactic measure, and has been shown to reduce the frequency of osteoporotic fracture. Until recently, few prospective studies of the effect of hormone replacement theraphy (HRT) on fracture risk had been published. The estrogen plus progestin component of the Women’s Health Initiative provided the first robust placebo-controlled data concerning the effects of HRT on fracture risk. The concept of combining an anabolic agent with an antiresorptive agent is attractive, and the addition of teriparatide to HRT gave significant improvements in bone mineral density (BMD). In contrast, anabolic agents can increase BMD by up to 20%.