Patients with osteoporosis are about 10 millions in Japan. Ninety percents of the cases are derived from aging process. Ten percents of cases derived from some diseases and drug side effects, mainly glucocorticoids. For the purpose of prevention against glucocorticoid-induced osteoporosis, American College of Rheumatology (ACR) made the first clinical guideline in 1996. Also, the Japanese Society for Bone and Mineral Research (JBMR) made the guideline on the management and treatment of glucocorticoid-induced osteoporosis in 2004. It recommends medication of bisphosphonates to patients, if they take or intend to take glucocorticoids for more than 3 months, and have fragility fracture or low bone mineral density or intake more than 5mg (prednisolone equivalent) a day. Dr.Keizo Ohnaka, who is studying the mechanism of osteoporosis, is giving a word of warning to keep the guideline because the guideline is applied to a civil suit in U.S.A..