A 43-year-old woman, whose physical findings were consistent with Marfan's syndrome, presented with acute chest pain. Transthoracic two-dimensional echocardiography demonstrated dilated ascending aorta with a circular shape intimal flap at the root level. Subsequently, the patient required transesophageal echocardiography (TEE), but during esophageal intubation, the patient developed acute pericardial tamponade which resulted in death in spite of cardiopulmonary resuscitation. Although, some investigators recommend TEE as the first choice of diagnostic method of aortic dissection, hemodynamic stability is very important during TEE study. Therefore, aggressive sedation may be required in the case of circumferential dissection of the ascending aorta to prevent the increases of the blood pressure and the heart rate which suggested an extensive tear of the aortic intima during TEE procedure.