Authors have reviewed a series of 41 cases of fibrous dysplasia which were treated surgically at the Department of Orthopedic Surgery, College of Medicine, Seoul National University. After mean follow-up of 25 months, we summarized the results as follows; 1. Among the 41 patients, 20 were male patients(M:F= 1:1.05). The average age was 20.2 years old. It was the most common in the 2nd decade(44%). The most common site was femur (53.6%) followed by tibia (28.6%) in monostotic type. Each polyototic patient had 3.8 locations in average. 2. The results were better in skeletally mature patients (86%) than in immature patients (42%). 3. Satisfactory results seemed to be expected in monostotic type (71%) than polyostotic type(33 %) 4. Satisfactory results seemed to be expected in sclerotic type(78%) than cystic type(50%) or ground glass appearance type (62%). 5. Autograft(71%) was superior to xenograft(40%) in our study. However, xenograft only or xenograft with autograft can be a recommendable method of treatment for a very large lesion or for a patient with insufficient graft donor site.