The term penetrating atherosclerotic aortic ulcer describes a condition in which an atherosclerotic plaque ulcerates and burrows through the internal elastic lamina into the media, leading to a variable amount of intramural hematoma formation. The typical patient is elderly with multiple cardiac risk factors and presents with acute chest or back pain. Diagnosis of penetrating aortic ulcer may be confirmed by computed tomography, magnetic resonance imaging or aortography. Penetrating aortic ulcers usually occur in the mid- and distal descending thoracic aorta and may be complicated by transmural aortic rupture, embolization, pseudoaneurysm formation, or progressive aneurysmal dilatation. The patient with a penetrating ulcer requires close follow-up to detect the development of complications, and may require surgical therapy.