Aortic dissection is a life-threatening cardiovascular emergency requiring immediate diagnosis and treatment. It is mainly associated with hypertension and the Marfan syndrome. Diagnosis has been revolutionized by the use of transesophageal echocardiography (TEE), which allows for rapid and safe assessment of this condition. Echocardiographic hallmarks of aortic dissection ar the presence of a dissection membrane separating a true from a false lumen, rupture sites in the membrane with to-and-from flow, aortic regurgitation, and pericardial effusion. Dissection of the ascending aorta, which has an extremely high mortality and necessitates emergency surgery, is diagnosed quickly and accurately by TEE.