Six patients with unilateral malignant astrocytomas were treated with pulse doses of intra-arterial BCNU [1,3-bis-(2-chloroethyl)-1-nitrosourea] (200 mg/m2 initially, with escalating doses every 6-8 wk) via transfemoral selective internal carotid catheterization. Four patients had had partial resections without prior radiation therapy and received no steroids. They had decreased tumor stain and surrounding edema after 2-4 cycles of chemotherapy. For 1 patient, results of the neurologic examination returned to normal, with total disappearance of her tumor as assessed by computerized tomographic scan. Objective tumor response continued for 7 mo. in 3 patients and for 3 mo. in 1. In 2 of the 4 patients, chemotherapy was discontinued because of retinal toxicity and not because of treatment failure. Two patients had had partial resections and radiation therapy. One patient had stable disease for 4 mo.; the 2nd had progressive disease with gradual visual loss beginning in the infused eye 3 wk after the 2nd treatment. The catheterization procedure is safe; it was without immediate complication in 17 BCNU infusions. High-dose intra-arterial BCNU is well-tolerated and is an effective initial chemotherapeutic modality.