Between 1977 and 1981, the Southwest Oncology Group entered 278 patients on a randomized study (SWOG 7703) to compare the effect of three different chemotherapeutic agents given in combination with radiotherapy (6000 rads over 7 weeks) following surgery for malignant gliomas. The chemotherapy regimens were: carmustine (BCNU)--80 mg/m2 iv daily X 3 every 6 weeks; procarbazine (PCB)--100 mg/m2 orally; or dacarbazine (DTIC)--175 mg/m2 iv daily X 5 every 4 weeks. Patients were stratified according to age, and degree of resection, with no differences identified between groups. The response rates (complete plus partial) for BCNU and DTIC were significantly better than for PCB [BCNU, 39%; PCB, 13%; and DTIC, 38% (P less than 0.01)]. The response duration and survival were somewhat better in patients treated with BCNU and DTIC, but compared to patients treated with PCB, the difference was not statistically significant. Median survival times were: BCNU, 45 weeks; PCB, 31 weeks; and DTIC, 49 weeks (P greater than 0.3). There were six toxic deaths with BCNU and four with PCB, most of which were due to infection associated with leukopenia. The high toxicity and minimal benefit of chemotherapy added to radiotherapy compared to historical results with radiotherapy alone suggest that combined treatment may not be indicated for some patients.