Extracranial-intracranial arterial bypass is a microneurosurgical procedure recently introduced in the treatment of a variety of cerebrovascular ischemic states. Fifty patients with transient ischemic attacks (TIAs) localized to the distribution of the internal carotid artery underwent this procedure during a 48-month period. All have been followed up for at least 14 months after surgery. There were no operative deaths, and notable postoperative morbidity has been experienced in less than 8% of cases. Seventy-six percent of patients have been asymptomatic since surgery, 14% have continued to experience TIAs, and 6% have had completed strokes (2% occurring in the operative hemisphere).