The incidence of glucocorticoid-induced osteoporosis is reported in about 40 to 50% of treated patients, but it has never been extensively studied in sarcoidosis. We have studied Vertebral Cancellous Mineral Content (VCMC) of the lumbar spine by Quantitative Computed Tomography (QCT) in 190 normal subjects, 7 patients with sarcoid on no treatment and 64 patients with sarcoid on treatment with prednisone. As compared to the 190 normal subjects and the 7 untreated patients, VCMC was reduced in 46 of 64 patients with sarcoid on treatment with prednisone. Loss of VCMC in the patients varied directly with dose and duration of prednisone treatment. It is concluded that - in sarcoid patients and especially in postmenopausal females - long-term prednisone therapy results in bone mineral loss more frequently than elsewhere reported for other groups of patients. It is not clear if this difference is due to the sarcoidosis itself or to the better sensitivity of Computed Tomography compared to former techniques.