Penetrating atherormatous ulcer (PAU) is the condition in which ulceration of an aortic atherosclerotic lesion penetrates the internal elastic lamina into the media. Penetrating atheromatous ulcers usually involve the descending thoracic aorta and are very uncommon in ascending aorta. Differentiation of PAU from other causes of Acute Aortic Syndrome (AAS) such as intramural haematoma (IMH) and aortic dissection is difficult. The diagnosis of these ulcers is made on computerised tomography (CT) scan, magnetic resonance imaging (MRI), or transoesophageal echocardiography (TOE). Once diagnosed, PAU of ascending aorta should be treated surgically on emergency basis. We report on a patient of penetrating atherosclerotic aortic ulcer in ascending aorta with a review of the natural history, imaging diagnosis and management of the condition. She underwent ascending aortic interposition graft using 26mm Dacron graft successfully.