&NA;The intravascular use of the rapidly polymerizing acrylic compound isobutyl 2‐cyanoacrylate in four patients with carotidcavernous fistulas is described. The monomer was injected into the cavernous sinus at craniotomy after the intraoperative angiographic identification of the fistula site and the origin of its venous drainage. All patients had postoperative angiographic documentation of fistula closure and confirmed carotid artery patency. There was no operative mortality or permanent neurological morbidity. Two patients (50%) suffered transient dysfunction in the immediate postoperative period of one of the cranial nerves that transit the cavernous sinus. (Neurosurgery8:52‐55, 1981)