The treatment with anti-resorptive agents including bisphosphonates and selective estrogen receptor modulators (SERM) has clinical relevance to reduce osteoporotic fractures in postmenopausal women. Among them, etidronate has a unique mechanism to suppress osteoclastic activity, and could be used to treat long-term immobilized patients, to whom other bisphosphonates or SERM are not available because of their adverse effects. In addition, intermittent therapy regimen (two weeks every three months) and less gastroesophageal reflux disorder may be suitable for some patients. Etidronate has less and lower clinical evidences than other bisphosphonates and SERM, but still has clinical efficacy and advantage to treat osteoporotic patients.