Twenty-two adults with ependymomas of the spinal cord were treated with surgery and postoperative radiation between January 1963 and December 1983. The median age was 47 years. Nineteen patients had grade 1 lesions, two had grade 2 and one grade 3. Ten patients had the myxopapillary histologic subtype (all grade 1) and 12 had the cellular variant. There were 15 distal cord lesions originating from the conus medullaris, filum terminale and/or cauda equina. The remaining seven lesions arose more proximally. Fourteen patients had localized lesions involving one to three vertebral segments, while the remaining eight had extensive ependymomas spanning six to thirteen vertebral segments. The median time from onset of symptoms to diagnosis was 3 years. Surgical treatment consisted of biopsy only in three patients, subtotal removal in eleven patients and total removal in eight patients. Radiation was given to the spine only in all cases. Five patients received whole spine radiation; seventeen received partial spine treatment, appropriate for the length of the primary lesion. The median dose was 5000 cGy (range 3600-5700 cGy). The disease free survival at 5 and 10 years was 81 and 71%, respectively. Overall survival at 5 and 10 years was 95%. Seven of twenty-two (32%) patients failed. Factors analyzed for prognostic significance included age, sex, histology, extent of primary, location of primary within the cord, extent of surgical resection and dose. Too few grade 2 and 3 patients precluded meaningful statistical analysis of grade as a prognostic factor. Neither age, sex, histology, extent of primary, location of primary, nor extent of surgical removal significantly affected disease free or overall survival (p greater than 0.05). Four of nineteen (21%) patients with grade 1 lesions failed, while all three patients with grade 2 and 3 lesions did so. Half of the eight patients with extensive ependymomas failed compared to three of fourteen (21%) with limited ones. Six of seventeen (35%) patients failed at doses less than or equal to 5000 cGy while only one of five (20%) failed at doses greater than 5000 cGy. Patterns of failure were analyzed for the seven patients who failed. Six of the seven failures (86% of the failure group, 27% of the overall group) were local, that is, within the initial radiation field at the site of the original tumor. A single patient (grade 2) failed in the posterior fossa while remaining NED in the spinal cord (a head CT scan at initial work-up was negative).(ABSTRACT TRUNCATED AT 400 WORDS)