Of the 2885 patients participating in the North American Symptomatic Carotid Endarterectomy Trial, 90 (3.1%) had unruptured intracranial aneurysms (UIA), of which 96% had a diameter of less than 10 mm. During an average 5-year follow-up, only one patient had subarachnoid hemorrhage 6 days after carotid endarterectomy (CE). For patients with unrepaired UIA, the 5-year stroke risk was 10% after CE and 22.7% with best medical care. Both risks are similar to those of patients without UIA. The decision regarding CE probably should not be influenced by the presence of a small UIA.