Infantile periarteritis nodosa is a rare disease characterized by systemic obstructive arteritis involving coronary artery. This report is anesthetic experience of a 12-years-old boy with unstable angina secondary to infantile periarteritis nodosa, who underwent left ventricular aneurysmectomy and coronary artery bypass grafting. Anesthesia was induced with fentanyl, diazepam and enflurane, and transesophageal echocardiography (TEE) was used as a cardiac function monitor. The following two intraoperative crises occurred in succession: first, aggravation of myocardial ischemia followed by ventricular tachycardia, and second, sudden interruption of cardiopulmonary bypass due to blood coagulation in membrane oxygenator. In these situations, we could detect his critical situations promptly, because segmental wall-motion abnormality and global enlargement of both ventricles were observed with TEE before the onset of these crises. In these crises, we could treat him appropriately. Postoperative course was uneventful and he had no neurological deficit nor angina. We conclude that TEE is a powerful non-invasive monitor for early detection of cardiac dysfunction in heart surgery.