Since 1978, We have experienced 87 cases of Fontan operations and the candidates of that increased in numbers recently with the improvement of the diagnostic and operative technique. We studied the prerequisite factors and hemodynamics of 22 cases of Fontan operations, done during the last one year period, which were 3 tricuspid atresia, 16 functional single ventricle and 3 anatomic single ventricle. The mean age was 68 months and the mortality rate 24%, and 9 patients of under 4 years of age were operated with 22.2% mortality rate, but the youngest, 16 months of age, patient survived well without problems. The preoperative pulmonary artery pressure[PAP], pulmonary vascular resistance[PVR] and postoperative right atrial pressure[RAP], left atrial pressure[LAP] value influenced the mortality, but age, preoperative Hb, preoperative PaO2 and pulmonary artery index[PAI] did not. There were favorable survival tendency in under 15mmHg of preop. PAP, 2a of preop. PVR and under 25cmHyO of postop. RAP, under 15cmHyO of postop LAP. The younger, the more pleural effusion and the longer postoperative admission days. The higher preop. Hb related to the higher postop. transpulmonary pressure gradient and the lower preop. PaO2 and PAI. The higher preop. PaO2, the less pleural effusion and postop. admission days. Preop. PAP closely related to preop. PVR and postop. LAP and high PVR increased the pleural effusion and postop. admission days. The larger PAI, the larger CI. We concluded that there were so many factors influencing the postoperative condition, but preop. PAP, PVR, Hb, postop. RAP and LAP were the most ones.