During the early postoperative period after coronary artery bypass grafting (CABG) surgery, many patients experience jugular bulb oxyhemoglobin desaturation (SjO(2) < 50%). We sought to determine whether SjO(2) during cardiopulmonary bypass and the early postoperative period influenced long-term cognitive performance after CABG surgery. One hundred two patients completed a battery of cognitive tests the day before and 3 mo after CABG surgery. A General Cognitive Score was generated from these tests as an overall measure of cognitive function. Intraoperatively, SjO(2) was determined by intermittent blood sampling, and postoperatively, the area under the curve of SjO(2) < 50% and time was calculated from continuous reflectance oximetry. No significant correlations between cognitive performance and either intra- or postoperative SjO(2) were found. Preoperative cognitive performance was the main determinant of cognition at 3 mo (r(2) = 0.83, P<0.001), and palpable atheroma of the ascending aorta made a small, but significant, contribution to a decline in cognition (r(2) = 0.018, P = 0.001).