Osteoporosis and fractures are the frequent consequences of corticosteroid therapy. Cancellous bone is primarily affected with a decrease of bone formation and an increase of bone resorption. Prevention of corticosteroid-induced osteoporosis is based upon general measures such as calcium and vitamin D supplementation, adequate protein intake, regular physical exercise, and upon specific therapies like those used in primary osteoporosis. Biphosphonates, which are potent bone resorption inhibitors, have been shown to increase bone mineral density and to decrease vertebral fracture rate. Therefore, they appear to be a first choice in the prevention of corticosteroid-induced osteoporosis.