Aminobisphosphonates are extensively used to prevent fractures in patients with osteoporosis (1-6). Treatment with these drugs leads to decreases in bone resorption and biochemical markers of bone turnover and progressive increases in bone mineral density (BMD). The increase in BMD in response to bisphosphonate therapy in glucocorticoid-treated patients is, however, less than half that measured in women and men with osteoporosis unrelated to glucocorticoid drugs even though the patients with osteoporosis are usually older. The goal of this objective is to determine the contribution of increased osteoclast survival to the diminished response to bisphosphonate therapy in patients receiving excess glucocorticoids compared to patients with osteoporosis.