Objective: Research investigating the benefits of carotid endarterectomy (CEA) on cognitive functioning remains inconclusive. This study sought to determine what patient characteristics affect cognitive functioning and whether changes in cognitive functioning occur following surgery after controlling for these characteristics. Methods: In a prospective longitudinal study, 39 patients scheduled for CEA surgery underwent neuropsychological testing in the week prior to their surgery. Two patients had a stroke following surgery, leaving 37 patients who were tested again at 7 days and 3 months following surgery. The surgery was performed under a locoregional anesthetic. Results: Patient characteristics associated with cognitive functioning were age, education, and IQ. In addition, differences in cognitive performance on a number of tests were related to presenting symptoms. Stroke patients (n = 6) differed significantly from symptom-free patients (n = 18) and patients with symptoms (n = 13) on measures of verbal fluency, visual search and mental flexibility, and verbal learning. When differences in patient characteristics were controlled for, no significant changes in cognitive functioning were found that could be attributed to the effects of surgery. Conclusions: No changes in cognitive functioning were associated with CEA. Differences in cognitive functioning, however, were associated with patient characteristics, including differences in presenting symptoms.