Pagets disease is a disorder of bone architecture resulting from a disturbance in the rate of bone turnover. It appears that early in the disease, an increased rate of bone tissue breakdown by osteoclast is followed by excessive bone tissue formation by osteoblast. Paget's disease has been well known in western countries, but is extremely rare in the orient. We experienced a case of Paget's disease in 77 years old man with olecranon fracture of nonaffected ulna.