We present findings of persistent left superior vena cava, anomalous right superior pulmonary venous return into the right-sided superior vena cava and a sinus venosus-type atrial septal defect detected incidentally by CT pulmonary angiography. To our knowledge, there has been no previous case report with all of the above findings detected by CT. In addition to the radiological findings and their clinical significance, the anatomy and embryological explanation of each anomaly is discussed.