A 36-year-old female was admitted for severe chest pain followed by profound shock. Electrocardiography showed severe ST segment depression (0.5-0.7 mV) in all leads except aVR and aVL. Echocardiography revealed an intimal flap in the ascending aorta and coexisting grade 3 aortic regurgitation. She was immediately intubated and transferred to the intensive care unit. Transesophageal echocardiography (TEE) demonstrated an intimal tear at 2 cm above the sinotubular junction, and the ostium of the left main trunk was oppressed by the intimal flap during diastole. Emergency graft replacement of the ascending aorta and aortic hemiarch concomitant with aortic valve resuspension was performed successfully. The ECG changes reversed to normal immediately after the operation. The patient was extubated 2 days postoperatively and discharged from the hospital 14 days postoperatively. TEE is useful for the rapid evaluation of coronary malperfusion as a complication of acute aortic dissection, especially in patients with hemodynamic instability.