Survival was analyzed in 173 patients with malignant gliomas to study the importance of possible pretreatment prognostic factors. Seventy-nine of these patients received preirradiation intra-arterial chemotherapy with BCNU combined with vincristine intravenously and procarbazine orally; the others received only postoperative whole-brain irradiation. To judge by univariate and multivariate analyses the most important pretreatment prognostic factors were histology, corticosteroid dependency, pretreatment performance status and frontal lobe location of the tumors. Patients with anaplastic astrocytoma, not corticosteroid-dependent, with pretreatment performance status of 0-2 and with a frontal lobe location of the tumor seemed to benefit most from preirradiation chemotherapy.