The Fontan principle of redirecting systemic venous blood into the pulmonary arteries via a conduit was initially proposed for Tricuspid Atresia, but it and its modifications have now gained a much wider application than initially intended. From September 1978 to July 1983, Atriopulmonary anastomosis has been performed in 23 patients, 2 months to 19 years of age, Seoul National University Hospital. The diagnoses were Tricuspid Atresia [TA] in 13, Univentricular Heart [UVH] in 9 and one case of Double Outlet of Right Ventricle [DORV]. Previous procedures included two Glenn shunts and one Blalock-Taussl8 shunt. Among these 23 patients, 10 patients had Right Atrial to Pulmonary Artery conduit, with a valve in 7 and without in 3. The remaining 13 patients had direct anastomosis between RA to PA. There were 14 early deaths, 7 of 13 TA patients, 6 of 9 UVH patients and one DORV, and the total hospital mortality was 60%. But there were no later deaths, 9 of these 23 patients survived operation and are presently alive. The Fontan procedure can be done with an acceptable low mortality with good functional results for Tricuspid Atresia and other complex lesion in foreign hospital, but till now our results revealed much higher risks. For our good operative results and effective patients selection, we must clarify the exact condition of pulmonary arterial system and accumulate much more experiences and technique. [KTCS 1983;3:342-348]