From November 1976 to September 1979, 46 patients with intracranial arteriovenous malformations or fistulas participated in a clinical study using isobutyl 2-cyanoacrylate (IBCA), with tantalum, for palliative or preoperative occlusion of the blood supply to the abnormalities. Although failure to obtain satisfactory position of a functioning microcatheter precluded deposition of IBCA 10 times, a total of 51 of a possible 62 feeding vessels were occluded with the tantalum-impregnated glue. The technique, results, and complications are discussed in light of the clinical follow-up, which varied from 12 to 48 months.