Acute aortic dissection (AAD) is a life-threatening condition for which prompt diagnosis is essential for successful management. The imaging modalities for demonstrating the dissecting membrane include retrograde aortography, contrast-enhanced computed tomography (CT), transesophageal echocardiography (TEE), and magnetic resonance imaging. Of these, aortography had long been considered the gold standard in diagnosing aortic dissection. We present a case of AAD in which contrast-enhanced CT and retrograde aortography failed to demonstrate an aortic membranous flap, whereas TEE swiftly provided clear-cut evidence of the pathology. TEE should be considered when AAD is suspected despite negative findings on other imaging modalities.