This study compared the occurrence of intraoperative microemboli and postoperative changes in neuropsychological performance in 195 patients undergoing coronary artery bypass grafting who were randomized to intermittent crossclamp fibrillation or cardioplegic arrest. Cerebral microemboli were recorded from cannulation to 15 min after decannulation, using transcranial Doppler in 166 patients. Microemboli in relation to 9 surgical events were also noted. Neuropsychological change scores were obtained by comparing cognitive performance preoperatively with that at 6-8 weeks after surgery. The median number of microemboli detected was 105 (range, 9-1,757) in the fibrillation group, and 110 (range, 1-1,306) in the cardioplegia group, with no significant difference between groups. There was also no significant difference between groups in the generation of microemboli during any of the surgical events. Neuropsychological tests were completed postoperatively by 177 participants, with no significant differences in performance found between the 2 groups. Given the equivalence of the effect of intermittent crossclamp fibrillation and cardioplegic arrest on microemboli and neuropsychology, consideration of which form of myocardial protection to employ should perhaps focus more on which method affords most protection to the heart.