Coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass (CPB) can produce a higher incidence of neuropsychological complications than other types of highly invasive noncardiac vascular surgery. Cognitive complications most likely arise from either embolization or hypoxia. An alternative surgical procedure has been developed that allows CABG to be performed without stopping the heart ("off-pump" CABG, or OPCABG). This study examined the neuropsychological performance of patients undergoing OPCABG, hypothesizing that patients undergoing OPCABG would show fewer cognitive deficits than patients whose hearts were stopped. A 1-hr neuropsychological battery was administered preoperatively to 43 patients before prospective randomization to either CPB CABG or OPCABG, and again to 34 of those patients 2 to 3 months postoperatively by an examiner blind to surgical condition. Neuropsychological status did not change 2.5 months postsurgically in either OPCABG or CABG groups. However, both groups showed dramatic presurgical cognitive deficits in multiple domains, particularly verbal memory and psychomotor speed. This corroborates previous research suggesting that patients requiring CABG surgery may evidence significant presurgical cognitive deficits as a result of existing vascular disease.