The concept of cytoreductive surgery in the treatment of glioblastoma multiforme is controversial. A retrospective study was carried out between 1986 and 1991 to analyze the results of stereotactic biopsy followed by supportive treatment (n = 49), incomplete radiation therapy (less than 40 Gy, n = 26), and complete radiation therapy (greater than or equal to 40 Gy, n = 58) and to compare with those of resection plus irradiation described in the literature. The patients treated with supportive care and an incomplete course of irradiation had a median survival of less than 8 weeks. For the patients who completed the radiation therapy the median survival was 32 weeks. In patients with midline shift the Karnofsky scores worsened more often during the course of radiation therapy, or therapy had to be terminated prematurely. The most important prognostic determinant was the patient's age. A comparison of survival rates in our series with those reported by other authors for patients who received tumor resection with subsequent irradiation yielded no significant difference. This would appear to cast doubt on the concept of cytoreductive surgery. The treatment of choice for patients with glioblastoma multiforme is at present radiation therapy. There is no question about the necessity of decompressive surgery whenever it is required to perform radiation therapy for severe space-occupying lesions and when it can be performed without causing new neurological deficits.