OBJECTIVE This study investigated the effects of low-dose tranexamic acid on post-coronary artery bypass surgery bleeding. BACKGROUND Diffuse microvascular bleeding is still a common problem after cardiac procedures. This study was designed to evaluate the hemostatic effects of low-dose tranexamic acid in on-pump coronary artery bypass graft surgery. METHODS In this prospective randomized placebo-controlled study, 150 patients who were candidates for coronary artery bypass were enrolled and randomly assigned to 1 of 2 groups (tranexamic acid or placebo). Total drainage volume and the need for transfusion as well as surgical complications were recorded and compared in the 2 groups. RESULTS There was significantly less mediastinal chest tube drainage up to 48 h in the tranexamic acid group (432 ± 210 mL) compared to the placebo group (649 ± 235 mL, p = 0.006). In the placebo group, 43 (58%) patients were given allogeneic blood during hospital stay compared to 22 (25%) in the tranexamic acid group (p < 0.001). No significant difference in postoperative complications was seen. CONCLUSIONS The use of low-dose tranexamic acid can significantly reduce blood loss and need for transfusion, with no increase in complications.