Dissection of the thoracic aorta is a life-threatening event that presents with some regularity to emergency departments (EDs). Despite often nonspecific symptoms, it is critical to catch this disease process early, especially when the proximal aorta is involved because dissections involving the aortic root can lead to myocardial infarction and failure of the aortic valve resulting in death. Current imaging options include contrast-enhanced chest computed tomography (CT), angiography, magnetic resonance imaging, or transesophageal echocardiography. Although not as accurate as transesophageal echocardiography, transthoracic echocardiography (TTE) can be used to detect aortic dissection as well. We present a previously undescribed echocardiographic finding associated with proximal dissection of the thoracic aorta in 7 cases. (Am J Emerg Med 2002;20:344-348.