From November 1988 to October 1991 30 patients underwent a total extracardiac right heart bypass for complex cardiac anomalies by means of bidirectional cavopulmonary anastomosis and interposition of a conduit from the inferior vena cava to the pulmonary artery. Mean age at surgery was 6.4 years and mean weight 19.2 kg. There was 1 hospital death (3%) due to a borderline indication for a Fontan operation. 2 patients had further surgery: In 1 the repair was taken down due to the stenosis of the left pulmonary artery and the patient was left with a bidirectional cavopulmonary anastomosis only, the second patient required a revision of the cavopulmonary anastomosis due to a stenosis of the superior vena cavaright pulmonary artery junction. There were no late deaths and the survivors are in good clinical condition a mean of 15.1 months after the operation. We propose this technique as an alternative surgical option in candidates for a Fontan operation in whom atrial septation is hazardous including those with 1) hypoplasia or atresia of the left atrio-ventricular valve, 2) common atrioventricular valve, 3) anomalies of systemic and/or pulmonary venous return, or 4) auricular juxtaposition.