Osteoporosis is frequently induced in patients on long-term glucocorticoid (GC) use and fracture associated with GC-induced osteoporosis is one of major problems. The measurement of bone mineral density (BMD) is useful for management and treatment of patients on GC use, especially for determination of medical treatment as well as evaluation of therapeutic effect. However, it should be recognized that bone of GC-treated patients would have severer fragility than estimated from BMD value, because there have been several lines of evidence that the cut-off value of BMD that discriminates patients with vertebral fractures from those without fractures is higher, compared with cut-off value obtained from GC-untreated patients. Therefore, other indices such as serum osteocalcin level and muscle strength in addition to BMD should be taken into account to predict fracture risk in GC-treated patients.