Primary spinal cord tumors are rare, and treatment recommendations are therefore difficult. We reviewed a 22-year experience of postoperative radiotherapy for spinal cord tumors to elucidate prognostic factors and recommendations. Twenty-two patients with spinal cord tumors were treated from 1969-1991. Ten patients had ependymomas, of which two were high grade. Twelve had astrocytomas, of which 4 were high grade. Karnofsky status, age, extent of resection, tumor histology, grade, and radiation dose were evaluated, as well as degree of clinical improvement after treatment based on change in Karnofsky status. Ependymomas achieved 100% local control with postoperative radiotherapy. Grade and dose were of indeterminate significance because of these excellent results. High-grade astrocytomas all recurred and caused death. Disease recurred in 1 of 8 patients with low-grade astrocytic or mixed astrocytic tumors. The only prognostic variables of significance were histology, grade, and change in Karnofsky status after treatment. Radiation of primary spinal cord tumors is rare. In nearly all cases, local fields may be used. Improvement in Karnofsky status after radiotherapy may predict better survival. Treatment recommendations for these rare tumors are discussed.