The effect of radiation therapy, either alone or combined with surgery or chemotherapy is accepted well in the treatment of metastatic carcinoma, multiple myeloma, reticulum cell sarcoma and Ewing's sarcoma. But its effect on osteosarcoma and chondrosarcoma is less clear. The authors reviewed 90 patients treated with radiation therapy, 62 cases with primary bone tumor and 28 cases with multiple myeloma, from 1969 to 1988. There were 20 Ewing's sarcoma, 12 osteosarcoma, 12 chondrosarcoma, 9 Histiocytosis-X and 3 reticulum cell sarcoma among 62 primary bone tumors. And 40 patients with more than three months follow-up were analyzed for the primary response of tumor three months after radiation therapy and the long term effect of the radiation therapy. When the radiation therapy was done alone, the primary response was poor in osteogenic sarcoma, chondrosarcoma, Ewing's sarcoma and reticulum cell sarcoma. But with the multimodal therapy, the primary response was rslatively good in reticulum cell sarcoma and chondrosarcoma. In 15 patients, more than one year follow-up was done. The status of these patients at the last follow-up was poor in all cases trearted with radiation therapy alone than the multimodal therapy except Histiocytosis-X. In multiple myeloma, the effect of radiation therapy for the relief of pain was analyzed. There were complete relief of pain in 14.3%, partial relief in 71.4% and no relief in 10.7%.