Glucocorticoid drugs interact with bone metabolism at many levels, but their principal action is to reduce osteoblast number and bone matrix synthesis. Virtually all patients receiving glucocorticoids in doses above 5 mg per day lose bone, the amount lost being dependent on the cumulative steroid dose. The risk of fracture is also related to the individual's initial bone density, which in turn reflects race, sex, age, menopausal status, body weight, smoking and the nature of any underlying illness. Bone density measurement and personal fracture history are the best predictors of future fracture risk. Steroid-induced bone loss is reversible, so measures to minimize the systemic steroid dose or to withdraw these drugs altogether should be pursued no matter how long an individual has been using them. Increasing the calcium intake to 1.5 g per day, encouraging them to stop smoking and take more exercise, and treating any vitamin D deficiency are sensible measures in all patients. In those at high risk, bisphosphonates are the best documented interventions, although sex hormone replacement is also effective and can be used alone or in addition to bisphosphonates.