While coronary artery bypass grafting operations (CABG), we started to use the echogram to evaluate the ascending aorta intraoperatively from December 1993. During a period from January, 1990, to June, 1995, 379 patients were treated with CABG. Intraoperative echogram was used in 127 cases (group I) and 252 cases unused (group II). The sites of the aorta for evaluation were following: site of cannulation, aortic clamping, and proximal anastomosis respectively. Depending on the echographical findings the operative procedures were changed as required. The incidence of postoperative cerebral embolism in group I was 0.8% (one patient) and in group II, 2.4% (6 patients). Although no significant difference was found in the cohort, rate of incidence in the group II was high. There were 4 cases who had significant atheromatous lesions clearly evaluated by echogram, which were not detected by palpation. We conclude that the intraoperative assessment of the ascending aorta by echogram is beneficial in prevention of cerebral infarction.