The authors report the results of a randomized study conducted to evaluate the relative benefit of treatment with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) or the combination of procarbazine, 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea, and vincristine (PCV) administered after radiation therapy with hydroxyurea to 76 evaluable patients with glioblastoma multiforme and 72 patients with other anaplastic gliomas. The primary end-point of the study was time to tumor progression. For better-risk patients with Karnofsky performance scores of 70 to 100, results suggest that PCV was of greater benefit than BCNU (p = 0.15 for glioblastoma multiforme; p = 0.13 for other anaplastic gliomas). Median times to tumor progression were 31 and 32 weeks for patients with glioblastoma multiforme; 25th percentile times to progression were 70 and 40 weeks for patients treated with PCV and BCNU, respectively. For patients with other anaplastic gliomas treated with PCV and BCNU, median times to progression were 123 and 77 weeks, respectively. Multivariate analysis showed that the prognostic variables of age and Karnofsky scores were important for patients with glioblastoma multiforme and other anaplastic gliomas, and that the extent of surgical resection was important for those with other anaplastic gliomas.