The results of the study were summsrized as follows;

l. Of the 152 cases of primary bone tumors, benign tumors were 128 cases(84.2%) and malignant tumors were 24 cases(15.8%).

2. Of benign bone tumors, the most common type was osteochondroms(34 cases, 26.6%), followed by fibrous dysplasia(25 cases, 19.5%), giant cell tumor(14 cases, 10.9%) and enchondroma(11 cases, 8.6%).

3. Of malignant bone tumors, the most common type was osteosarcoma(14 cases, 58.3%), followed by chondrosarcoma(5 cases, 20.8%), Ewing's sarcoma(3 cases, 12.5%) and myeloma(1 case, 4.2%).

4. Age distribution of benign bone tumors showed that most cases(76.4%) occured under 30-years old. Among malignant bone tumors, most of osteosarcoma and Ewing's sarcoma occured between 10-and 20-yesrs old.

5. The male to female ratio of overall benign bone tumors was 1.1: 1, and that of maligant bone tumors was 1.2: 1. There was no sexual difference.

6. The favorite sites of benign bone tumors were femur(31 cases, 23.1%), maxilla or mandible(31 cases, 23.1%), tibia(22 cases, 16.4%) and rib(11 cases, 8.2%) and those of malignant bone tumors were freguently femur(12 cases, 50.0%), followed by tibia(5 cases, 20.8 %) and pelvis(4 cases, 16.7%). 7. The most frequent manifestations in benign bone tumors were mass or swelling(62.7%), followed by pain or tenderness(33.9%) and disturbed motion or function(10.2%), but those were mostly pain or tenderness(73.9%), followed by mass or swelling(52.2%) and pathologic fracture(13.0%) in malignsnt bone tumors.8. The duration of symptoms in benign bone tumors was less than 6 months in 39.1% and less than 1 year in 44.6%, but less than 6 months in 70.9% and less than 1 year in 87.6% in malignant bone tumors. The duration of symptoms in malignant bone tumors was much shorted than that of benign bone tumors.