Therapeutic embolization is now used widely for the treatment, either definitive or preoperative, of vascular lesions within areas supplied by the carotid arteries. Its place in the treatment of arteriovenous fistulas, malformations, and vascular tumors fed largely by the external carotid artery is established, although some of the newer embolic materials have not been fully proven. Balloon catheters appear to represent an important method for treating internal carotidcavernous sinus and similar fistulas. Embolization of cerebral lesions is still practiced on a much smaller scale, and questions as to its efficacy and safety have not been resolved.