Chronic glucocorticoid treatment is the most frequent cause of secondary osteoporosis. The direct inhibitory effect of glucocorticoids on osteoblasts results in decreased bone formation. Increased osteoclastic bone resorption due to low concentrations of gonadal steroid hormones and glucocorticoid-induced direct suppression of intestinal calcium absorption also contribute to the decrease of bone mass in these patients. Bone loss is rapid, particularly in the first months of glucocorticoid therapy. Bone mineral density of the lumbar spine and proximal femur should be measured in patients who are starting chronic therapy with glucocorticoids. Although glucocorticoid-induced osteoporosis is a severe and nowadays partially preventable disorder, osteoporosis prophylaxis is only rarely prescribed to these patients. Recent randomized, controlled trials proved the therapeutic effects of hormone replacement therapy, as well as of bisphosphonates and active vitamin D analogs in primary and secondary prevention of glucocorticoid-induced osteoporosis.