In open heart surgery negative effect of cardiopulmonary bypass on coagulation system increases postoperative bleeding. Tranexamic acid and desmopressin were used in order to eliminate fibrinolyzis and platelet disfunction arising as a result of that negative effect of CPB. 40 patients undergoing elective coronary artery bypass operations were studied, one group of 20 patients (group I) given tranexamic acid (10 mg/kg infusion over 20 minute followed by an infusion of l mg/kg for 10 hours) and desmopressin (0.3 mg/kg infusion over 20 minute) and one subsequent group of 20 patients (group II) serving as a control group. All patients were treated by the same team and the groups comparable in all major clinical parameters. The mean mediastinal drainage in group I was 501.5±106 ml versus in group II 778.0±157 ml. Patients in the placebo group received more fresh-frozen plasma. We conclude that prophylactic tranexamic acid and desmopressin can be administered safely to decrease postoperative bleeding and possibly decrease the frequency of blood product transfusion.