A total of 115 patients were randomly assigned to one of six therapeutic groups within 3 weeks from craniotomy as part of the Brain Tumor Study Group protocols. In category A (surgery without radiotherapy) there was no significant difference in survival between supportive care only and chemotherapy (BCNU or methyl-CCNU) groups. More than one half of patients in this category died within 6 months of surgery. In category B the addition of 6000 rad of whole-brain radiation treatment to the surgery increased survival time significantly: the 6-month survival rate was two to three times that observed in category A. More than 50% of patients were alive at 1 year and at least 20% survived 2 years. The best survival rate in this study was obtained in patients who received methyl-CCNU with irradiation. The duration of survival was increased to nearly two times that of the radiotherapy group and to six times that of the surgery only group. Reasons for this are discussed.