A total 73 cases of primary malignant bone tumors was reviewed and analysed clinically at the department of orthopaedic surgery, Kosin medicsl center, Pusan, Kores for 11 years from January, 1975 to December, 1985. The results were obtained as follows ; l. In the 73 cases of primsry malignant bone tumors, osteogenic sarcoma was the most common primary malignant bone tumor (57%) and followed by chondrossrcoma (10%), multiple myeloma (8%). 2. Average survival times according to each primary malignant bone tumors was more than 3 years in chondrosarcoma, reticulum cell sarcoma, and synovial sarcoma, 28 months in osteogenic sarcoma, and 7 months in Ewings sarcoma. Ewings sarcoma had the worse prognosis and the slowly progressing tumors-chondrosarcoma, reticulum cell sarcoma and synovial sarcoma are needed long term follow up. 3. In osteogenic sarcoma, the prognosis was better when developed in their 3rd decsde than when developed in their 2nd decade. 4. There is a slight difference in average survival time on the location of the site, for example when tumor is located in the distal femur, the prognosis was worst. 5. There is no difference in the prognosis. The mode of treatment did not effect to their prognosis. 6. It was clear that the tumors which had not been responded to chemotherapy or radiation therapy had poorer prognosis. Chondrosarcoma, fibrosarcoma and synovisl sarcoma were considered as slowly progressed tumors, and so it may be benefit to the patients that chemotherapy and/or radiotherapy were prescribed.