The hemostatic effect of tranexamic acid on the bleeding tendency and transfusion requirements in patients undergoing off-pump coronary artery bypass surgery was assessed in a prospective randomized double-blind study. Of 66 patients undergoing elective operations, 33 were given tranexamic acid (15 mg x kg(-1) before infusion of heparin and 15 mg x kg(-1) after protamine infusion), and the other 33 received only saline. Postoperative bleeding, transfusions, complications, hematological variables, and plasma D-dimer levels were recorded. Postoperative blood loss was significantly less in the tranexamic acid group compared to the control group (320 +/- 38 vs 480 +/- 75 mL). Patients in the tranexamic acid group received significantly less allogeneic blood products (0.46 vs 0.94 units per patient), and they had lower postoperative D-dimer levels. No postoperative thrombotic complications were observed in either group. Although off-pump coronary artery bypass surgery is associated with reduced frequency of hemorrhagic disorders, defective hemostasis still occurs, and tranexamic acid effectively reduces postoperative blood loss and the need for allogeneic blood products.