We sought the relationship between the pulmonary artery development and cardiac performance from the analysis of the 36 cyanotic congenital heart disease patients [mainly TOF] who were operated and indwelled the pulmonary artery and left atrial pressure monitoring catheters for the postoperative care at the department of Thoracic and Cardiovascular Surgery SNUH in 1988. They were pre-evaluated of the pulmonary artery index from the cineangiographic films and post-operatively, calculated the cardiac index from the arterial and mixed venous blood gas and also measured the mean left atrial pressure and total inotropic supporting amount after operation. The post-operative cardiac indices were 3.46 * 1.03 1/min/M2 [immediate postoperative], 3.31 [ 1.08 [postoperative 6 hrs], 3.29 [ 1.01 [12 hrs], 3.54 * 1.02 [24 hrs], 3.92 * 1.14 [48 hrs], respectively. We divided the patients the group A and group B from the size of the pulmonary artery index, that is, group A was below 200 mm2/M2 and group B above 200 mm2/M2 of the pulmonary artery index. The cardiac indices and left atrial pressure between the group A and B were not different in the view of the statistical significance but the total post-operative inotropic amount of group A was more than group B and it was significant statistically. We concluded that the smaller the pulmonary artery index is, the more postoperative supportive treatment [for example, inotropics] for the enhancement of cardiac performance is needed, and indirectly, which means that the pulmonary artery index was correlated with the postoperative cardiac performance in cyanotic congenital heart disease.