Routine computed tomography was prospectively performed pre- and postoperatively in 114 consecutive patients undergoing a total of 131 procedures on the carotid artery. Hemispheric cerebral infarction was found preoperatively in three of the 16 hemispheres corresponding to symptomatic lesions (19%), in 18 of 109 hemispheres corresponding to transient ischemic attacks (16.5%), and in one of four hemispheres corresponding to lesions responsible for a fixed cerebral vascular accident (25%). Two surgical procedures (1.5%) were complicated by early cerebral infarctions as detected on postoperative computed tomographic scan. These complications resulted in death in one case, and left the patient with major sequelae in the other. Five procedures (3.8%) were complicated by transient ischemic attacks, three of which were associated with minimal cerebral infarctions visible on computed tomographic scan. Neurologic status was unchanged after 124 (94.6%) procedures, whereas four of these procedures were complicated by silent brain infarctions as visualized on postoperative computed tomographic scans (3.1%). This study confirms that existing pre- and postoperative neurologic classifications are far from perfect and that surgery is rarely responsible for cerebral infarction. Carotid surgery should no longer be performed without obtaining pre- and postoperative computed tomographic scans.