Two hundred fifteen patients with a history of either stroke, transient ischemic attack (TIA), or asymptomatic carotid bruit underwent noninvasive carotid artery testing using oculopneumoplethysmography. Of patients with hemodynamically significant stenosis, 51 (40.8%) underwent endarterectomy, and 74 (59.2%) were treated nonoperatively. The incidence of stroke in the nonoperated group was 12/74 (16.2%) compared with only 1/51 (1.9%) in the operated group. Similarly, recurrent TIA occurred in 29/74 (39.2%) of the nonoperated group vs 9/51 (17.6%) of the operated. In nonhemodynamically significant carotid stenosis, the risk of cerebrovascular death and stroke was exceedingly low: 2/90 (2.2%). Patients with hemodynamically significant stenosis treated nonoperatively have a greater risk of cerebrovascular death, stroke, and TIA than patients treated with carotid endarterectomy.