A 56-year-old man visited our hospital for further examination of resting electrocardiographic abnormality. Positive exercise stress resulted in mild chest discomfort and 1.5 mm ST depression in II.III.aVF leads. Myocardial imaging perfusion with thallium-201 was normal and an anomalous origin of the left circumflex coronary artery from the right aortic sinus was observed by coronary angiography. MRI showed that the vessel running behind the aorta was connected to the right Valsalva's sinus. Furthermore, transesophageal echocardiography revealed that the vessel connected to the lateral wall of the left ventricle was running from the right Valsalva's sinus between the aorta and left atrium. The above results indicated that this vessel was the left circumflex artery. Although myocardial infarction or sudden death in patients with coronary anomaly has been discussed, the mechanism is still unknown. The present case is a rare one in which the anatomical relation between the anomalous coronary and the great vessels was directly detectable by transesophageal echocardiography. Transesophageal echocardiography is useful for the assessment of this type of coronary anomaly.