Abstract： Objective To compare individualized protamine with protamine based on weight in terms of postoperative bleeding and blood transfusion dose, in order to reduce postoperative bleeding complications. Methods Forty adult patients scheduled to elective open heart surgery under cardiopulmonary bypass （CPB） were randomly divided into two groups. For patients in the experimental group, we gave them protamine based on heparinprotamine titration result, while patients in the control group received the same amount of protamine as the heparin administered before operation. Pleural drainage and required transfusion were recorded at 1, 2 and 24 hours after surgery. Results Protamine dose given to the experimental group was significantly higher than the control group (Plt;0.05), while pleural drainage was significantly lower at 1 h(180±83 ml vs. 285±156 ml,P=0.012), 2 h (74±31 ml vs. 114±44 ml，P=0.002), and 24 h (465±167 ml vs. 645±207 ml，P=0.004) than that in the control group after surgery, and the required red blood cell suspension was also significantly lower than the control group (0.15±0.27 U vs.0.80±0.96 U,P=0.018). Conclusion Compared with protamine dose based on heparin administered before CPB, individualized protamine based on titration can reduce postoperative pleural drainage (blood loss) and red blood cell suspension requirement.