A pilot study was performed combining cis-diamminedichloroplatinum (CDDP) and radiation therapy to treat patients with high-grade astrocytomas. CDDP at a dose of 40 mg/m2/week intravenously was given during the course of cranial irradiation. Following irradiation, CDDP was given every three weeks on a schedule of 35-40 mg/m2/day for three days until toxicity became unacceptable or until tumor progression occurred. Radiation therapy consisted of 6 000 rads over a seven week period or 5 000 rads followed by an additional 1 500 rads to the tumor site. Patients were followed by computerized axial tomography (CT) scan and neurologic examination. Thirty patients were entered onto the study; 22 were considered evaluable. The median survival was 53 weeks and the median time to progression was 21 weeks. Toxicity was generally tolerable; however, ototoxicity may be enhanced by this treatment. CDDP combined with cranial irradiation is tolerable and feasible, although close follow-up is recommended in case CDDP has to be temporarily interrupted.