The persistent left superior vena cava (LSVC) is not rare cardiovascular developmental anomaly occurring both in association with congenital heart disease and as an isolated anomaly of no hemodynamic importance. We have studied 73 cases of the LSCV out of 1,060 cases of congenital heart disease catheterized at Yonsei Cardiovascular Center. We conducted the study with a view point of position of the heart and abdominal organs and segmental analysis of the underlying congenital heart disease. We also analysed the associated extracardiac vascular anomalies. The following results were obtained: 1) The incidence of this anomaly among congenital heart disease was 6.9% and 41 cases(56.2%) had cyanosis. 2) We observed 20 cases(27.3%) with the malposition of the heart and 17 cases(23.3%) with malposition of the abdominal organs. The ventricular loops revealed D-loop in 60 cases, L-loop in 7 cases and in the remaining 6 cases, it was uncertain. 3) With a view point of type of LSVC by Lucas & Krabill, type A was in 50 cases(68.5%), type D in 14 cases(19.2%), type B in 5 cases(6.8%) and type C in 4 cases(5.5%). 4) Associated cardiovascular anomalies were as follows: ventricular septal defect; 42 cases(57.5%), atrial septal defect; 33 cases(45.2%), patent ductus arteriosus; 27 cases(36.9%), and tetralogy of Fallot; 18 cases(24.7%). In conclusion, LSVC usually has no hemodynamic importance, but this cardiac anomaly is frequently combined with complex intracardiac anomalies. Therefore, it is important to making accurate diagnosis and successful management for preventing the risk of it.