Colloid solution is commonly used to increase the oncotic pressures of priming solutions used in the cardiopulmonary bypass circuit. To study the effectiveness of this practice, we retrospectively evaluated 24 patients undergoing cardiac operations to receive isoelectric solution plus 50 gm of albumin[group A], isoelectric solution plus 25 gm of albumin[group B] and isoelectric solution without albumin[group C] as the prime solution for the bypass circuit. Various clinical parameters related to the perioperative fluid balance, cardiopulmonary function, and renal function were studied. There were no differences between the three groups with regard to postoperative clinical parameter of cardiopulmonary, liver function and renal function. But at the previous report by Cho et al. [38], there was a significant difference between groups with regard to hematologic property, especially in crenated red blood cells. These hematologic events did not affect the clinical outcome but thorough evaluations are needed in order to prove the clinical effect of crenated red blood cell. We conclude that there is no clinically detectable advantage for the routinely supplementing of albumin to the priming solution of bypass circuit in cardiac operations. Whether this practice can be of value in selected cases needs to be further studied.