Transesophageal echocardiography(TEE) was used for 18 patients undergoing the internal thoracic artery to the left anterior descending artery bypass grafting on beating heart between October 1999 and May 2000. Patients were aged from 58 to 79, averaged 68.1 years old. Gender was 13 in male. There were no significant differences in the effects of placement of two types of stabilizer, CTS and Octopus2, on left ventricular inter-nal diameter in diastole and systole, end diastolic volume, end systolic volume, ejection fraction, and cardiac output. However, peak systolic meridional wall stress(PSS) tended to reduce in patients without an intraluminal shunt tube as compared with those with the tube. Therefore, intraluminal shunt tube seems to be effective to avoid regional ischemic stress. TEE would be a useful monitor of the left ventricular performance during the off pump CABG.