Atherosclerotic and dysplastic aneurysms of the extracranial internal carotid artery are rare in Japan. We have experienced only four cases since 1982. The patients were two men and two women with a mean age of 67 years (range 51 to 82 years). All four patients had a saccular type aneurysm; sizes ranged from 30 to 75 mm. Aneurysmectomy and end-to-end anastomosis of the internal carotid artery could be performed in two patients. One patient underwent aneurysmorrhaphy followed by primary closure of the internal carotid artery, and the remaining patient underwent aneurysmectomy followed by a prosthetic graft replacement (6 mm-PTFE graft). During aneurysm repair, simple arterial cross-clamping (time 18 to 57 min; mean +/- SD: 31.3 +/- 18.0 min) was used in all patients. During arterial clamping of the carotid artery in two patients, somatosensory evoked potentials and regional cerebral oxygen saturation detected by near-infrared spectroscopy remained within normal ranges. All patients survived without neurologic deficits. These findings indicate that intraluminal shunting may be unnecessary during aneurysm repair if the patient does not have obstructive disease in the contralateral carotid artery and if no somatosensory evoked potentials or regional cerebral oxygen saturation abnormalities occur during proximal arterial clamping. After aneurysmectomy, end-to-end anastomosis of the internal carotid artery is the preferred method of repair if the length of the distal internal carotid artery permits.