We report five patients with anterior choroidal artery syndrome after surgery for internal carotid artery aneurysms. All patients suffered hemiparesis, and hemisensory loss and homonymous hemianopsia were identified in 2 patients. The characteristic triad of the syndrome was recognized in only 1 patient. Dominant and nondominant cerebral hemisphere signs have been reported in association with this syndrome, and 2 patients had a speech disturbance in our series. In previous reports, neurological deficits were mild and patient prognosis was good in anterior choroidal artery infarct, in spite of the fact that the artery supplied the corticobulbar and corticospinal tracts. This report suggests the possible causes of this syndrome after surgery for internal carotid aneurysms, which involve vasospasm after subarachnoid hemorrhage, mechanical obstruction, thromboembolism, and distortion of the aneurysm clip.