Congenital anomaly of IVC is rare, but understanding of this anomaly is important in radiological diagnosis, angiographic procedures and mojor retroperitoneal and thoracic surgery. We analysed 23 cases of IVC interruption diagnosed by cardiac angiography at Seoul National University Hospital. The results were as follows : 1. The incidence of infrahepatic interruption of IVC was 0.45% of the patients having cardiac angiography and most patients showed cyanosis(91%). 2. The most common associated cardiac anomaly was right ventricular outflow tract obstruction(60%). Other associated cardiac defects were VSD, ASD, valvular anomalies in 9 cases(39%) respectively : double outlet right ventricle, bilateral superior vena cava, single ventricle in 6 cases(26%) repectively : single atrium, PDA in 5 cases (22%) repectively. 6 cases of situs inversus, 3 cases of situs ambiguus, 2 cases of visceral heterotaxia and one case of asplenia were observed also. 7 case of left-sided IVC were assoc ated with IVC interruption in normal situs.