Objective To compare the efficacy of 6-epsilon-aminocaproic acid （EACA） with aprotinin on reducing postoperative bleeding in cardiac valve replacement procedures, and to investigate its influence on the possible thromboembolism and the renal function. Methods Seventy-nine patients who underwent cardiac valve replacement were randomly divided into two groups： EACA group （n = 39） and aprotinin group （n = 40）, which were given EACA and aprotinin separately in operations. The volumes of drainage to body surface area （BSA）, blood transfusion were recorded during 24 h after operations. The concentrations of serum D-dimer and α2-antiplasmin （a2- AP） were measured before, during operation and at 72h post-operatively. The serum creatinine levels before operation and at the 72 h after operation were also measured. Results The volume ratio of drainage to BSA in EACA group was significantly higher than that in the aprotinin group at 24 h after operation （P = 0. 019）. However, there was no significant difference in the volumes of blood transfusion between two groups （P〉0. 05）. Also no statistical difference in the concentrations of D-dimer and a2-AP were found between two groups whether preoperatively or at 72h post-operatively （P= 0. 960,0. 485）, D-dimer and a2-AP of the aprotinin group were higher than those in the EACA group after aortic off-clamping （P = 0. 001,0. 000）. There was no statistically difference of △CrCl72 in both groups （P〉0. 05）. No patient with thrombosis or thromboembolism was detected in two groups.Conclusion Although the efficacy of EACA in reducing postoperative bleeding in cardiac valve replacement can not compare favorably with that of aprotinin, the blood transfusion volume would not increase when EACA is used introoperatively. Proper usage of EACA will not cause thrombosis and renal damage.