Giant cell tumor of bone is an uncommon primary bone tumor and is predominantly an afflication of adults with the highest incidence in patients 20 to 40 years of age is rarely found in skeletally immature patients. These tumors are most frequently found in metaphyseal epiphyseal region of the long bones, especially around the knee joint and distal end of the radius. The presence of destructive lesion of bone was frequently situated eccetrically. The tumor on occasion invaded the articular space, also involving the ligaments and synovial membrane. So the normal life expectency and active life style of the patient necessitate a reliable and durable surgical remedy for eradicating the tumor and preserving joint fuction. Although almost always benign, these tumor are locally aggressive and tend to have a high rate of recurrence, and malignant transformation is well known to be 6-15%. Thus the lesions produce a practically difficult therapeutic problem for the orthopaedic surgeon, and a satisfactory method of treatment has not yet been found. Clinical observations were carried out on 10 cases of giant cell tumor of bone in department of orthopaedic surgery, Chungnam National University Hospital from May, 1983, to August, 1988, The follow up period was over two years. The results obtained were as follows. 1. The highest incidence, 7 cases (70% ), occurred in the 21-40 year old age group, and the sex distribution was 6 males and 4 females. 2. The location was distal femur in 7 cases (70% ), proximal tibia in 3 cases (30% ). 3. Roentgenologically the most cases showed an egg sized radiolucent bony defect, expanded, and thin cortex, or destructed cortex but in 4 cases pathological fracture was noted. 4. The pathologic grading according to Jaffe's criteria showed 3 cases (30%) in grade I, 6 cases (60%) in grade II and 1 case (10%) in grade III. 5. As the primary treatment modality, curretage and bone graft were performed in 3 cases, curretage, bone graft and bone cementing in 7 cases, and no patient required and En bloc resection, amputation or disarticulartion after primary treatment. 6. 1 of 7 tumors treated by curretage, bone graft and bone cement after primary treatment recurred within 3 years.