A 21 years old male student was admitted because of mediastinal mass that was noticed in routine physical examination. He complained progressive hoarseness, mild dysphagia, and anterior chest pain on deep respiration. This mediastinal mass was diagnosed as aortic aneurysm involving ascending, transverse, and descending thoracic aorta with aid of aortogram. Total prosthetic replacement of aneurysm was performed successfully using extracorporeal circulation and hypothermia. For myocardial protection during aortic cross clamping, cardioplegic solution was used and topical myocardial cooling was also adapted For simplicity of cardiopulmonary bypass, Y-shaped connectors took cerebral perfusion catheters to the main perfusion line beyond the arterial pump. Total bypass time was 219 minutes, and aortic cross clamp time was 104 minutes. Recovery was uneventful except respiratory insufficiency for first 4 days. Isotope aortogram checked on post operative 30th day showed normal aortic configuration. He was discharged on post operative 35th day. A follow-up chest X-ray study 5 months later showed nearly normal anatomy.