Of 34 evaluated patients with primary spinal cord tumors, 32 were irradiated at our institution between 1969 and 1983. The results are reported of 32 patients,10 with ependymoma and 16 with astrocytoma, who were treated with post-operative external beam radiotherapy following biopsy or subtotal resection. Twenty-nine patients received 45~55 Gy megavoltage beam irradiation in 5~6 weeks and the remaining three patients received less than 40 Gy. Spinal cord was in the irradiated field for six patients who received more than 50 Gy. The minimum follow-up was five years. Five and ten year acturaial survival rates for entire group of patients were 73%(22/30) and 50%(8/16), including three patients who were salvaged by surgery after radiation failures. Corresponding five and ten year relapse free survival rates were 60%(18/30) and 32%(6/19), respectively. Of the 29 patients who received more than 45 Gy, relapse free survival at five years was 63%(17/27). Treatment failed in 13 patients and all of those failures were in the irradiated portal. Patients with ependymomas have significantly better relapse free survival than those with astrocytomas, 80% vs. 40%(p<0.05). There was significant difference in survival between patients with tumors involving the cervical spine and those with tumors in the other loactions, 45% vs. 89%(p< 0.05). There was no significant difference in survival between patients with cauda equina tumors and those with tumors at spinal cord, 100% vs. 68%(p>0.05). No radiotherapy related neurological deficit was noted with a maximum 20 year follow-up. This study confirms that external beam radiotherapy is a safe and effective treatment modality for primary spinal cord tumors.