Objective: Postoperative bleeding is still one of the most common complications of cardiac surgery. Antifibrinolytic agents successfully reduce bleeding, but there are controversies concerning adverse effects after their systemic use. By topical application of antifibrinolytic agents in pericardial cavity, most of these effects are avoided. We compared the effects of topically applied aprotinin, tranexamic acid and placebo on postoperative bleeding and transfusion requirements. - - - - - Methods: In this single-center prospective, randomized, double-blind trial, 300 adult cardiac patients were randomized into three groups to receive one million IU of aprotinin (AP group), 2.5g of tranexamic acid (TA group) or placebo (PL group) topically before sternal closure. Groups were comparable with respect to all preoperative and intraoperative variables. Postoperative bleeding, transfusion requirements and hematologic parameters were evaluated. - - - - - Results: Postoperative bleeding within first 12-h period (AP group 433+/-294 [350; 360]ml, TA group 391+/-255 [350; 305]ml, PL group 613+/-505 [525; 348]ml), as well as cumulative blood loss within 24h (AP group 726+/-432 [640; 525]ml, TA group 633+/-343 [545; 335]ml, PL group 903+/-733 [800; 445]ml), showed statistically significant inter-group differences (both p<0.001). Bleeding rates values were significantly higher in placebo group compared to the groups treated with antifibrinolytic agents (AP and TA groups) concerning both variables. Although TA group showed the lowest values, no statistical differences between TA and AP groups were found. Inter-group difference of blood product requirements was not statistically significant. - - - - - Conclusions: Topical use of either tranexamic acid or aprotinin efficiently reduces postoperative bleeding. TA seems to be at least as potent as aprotinin, but potentially safer and with better cost-effectiveness ratio.