Truncus arteriosus (TA), a rare complex congenital cardiac disease in which systemic pulmonary and coronary circulations originate from a common vessel, develops due to failure of separation of the common trunk during embryonic life. In this case report, we discuss a 24-year-old patient with TA in whom a computed tomography angiography was performed. To the best of our knowledge, no case has been reported so far where an adult had combined left superior vena cava and pulmonary vein anomaly.