Intraoperative transesophageal echocardiography (TEE) was performed on a 53-yr-old man scheduled for the venous graft in the left leg under general anesthesia. The TEE revealed the severe mitral valve vegetation and because of the finding, the operation was cancelled. Preoperative transthoracic echocardiography showed mitral valve regurgitation only, and not mitral valve vegetation. TEE was useful not only in assessing global and regional cardiac function, but also in visualizing anatomic abnormalities of the heart and their influence on cardiac performance.