A retrospective analysis is presented of factors affecting the length of survival of 285 consecutive adults with newly diagnosed biopsy-proven supratentorial anaplastic glioma (188 cases of glioblastoma multiforme, 76 of anaplastic astrocytoma, 11 of anaplastic mixed glioma, and 10 of anaplastic oligodendroglioma) treated at a regional cancer center from July, 1982, through December, 1987. The approach to initial therapy included maximum feasible resection and radiotherapy. The median survival time for all patients was 35 weeks. Multivariate analysis demonstrated that age, duration of symptoms, preirradiation performance status, tumor histology, accessibility to resection, extent of resection, radiotherapy, and prior low-grade glioma were significant independent variables influencing survival. The prognostic importance of age, duration of symptoms, performance status, and tumor histology are already recognized, but three "new" findings are reported. First, patients with anaplastic oligodendroglioma had the longest median survival time (278 weeks). Second, corrected for accessibility and all other variables, patients with gross total resection lived longer than those with partial resection, and patients with any degree of resection lived longer than those who underwent only a biopsy procedure. Third, patients with anaplastic glioma in whom there was a prior history of low-grade glioma lived significantly longer after the diagnosis of anaplastic glioma than did patients in whom the anaplastic glioma apparently arose de novo.