The left ventricle is realized as the cardiac structure of greatest importance for cardiac pump function, and the role of the right ventricle has been overlooked. However, the right ventricle and the left ventricle are in series and physiologically coupled so that a disturbance in the one ventricular function will influence the behavior of the other. Thus, there ia growing interest in the importance of the right side of the heart, particularly in patients undergoing cardiac surgery. Moreover recently, right ventricular failure has been identified as a cause of progressive deterioration in patients undergoing cardiac operations, and it may limit the overall success of the procedure. This study was performed to investigate right ventricular ejection fraction of the cardiac patients at pre and post-perfusion period. 10 cases were measured and analyzed. The results were as follows: I) There were no singificant differences statistically in demographic data of the patients. 2) Pulmonary capillary wedge pressure(PCWP) of postperfusion 10 min. was significantly increased compared to preperfusion period(p<0.01). 3) Systemic vascular resistance(SVR) of immediate postperfusion period was significantly decreased compared to preperfusion period. 4) Heart rate and central venous pressure(CVP) of postperfusion period were statistically significantly increased, but clinically no significant change compared to preperfusion period. 5) Cardiac output(CO) and right ventricular ejection fraction(RVEF) of postperfusion period were no significant change compared to preperfusion period.