Background. The objective of this study was to study the effect of low-dose tranexamic acid (TA) on postoperative bleeding and coagulation variables after coronary artery bypass grafting operation. Methods. Fifty patients undergoing primary coronary artery bypass grafting were randomly assigned to receive either placebo (0.9% NaCl; n = 25) or 10 mg/kg TA followed by infusion of 1 mg/kg per hour during the operation (n = 25). Data measured included blood loss, transfusion, reoperation, fibrinogen level, fibrinogen split products, platelet size, and platelet function. Measurements were made after induction of anesthesia, after heparin administration, during patient warming, after skin closure, and 24 hours after operation. Results. Patients in the TA study group weighed less. Other demographic characteristics were similar between groups. Postoperative bleeding was less in the TA group (194 ± 135 mL versus 488 ± 238 mL, p < 0.001), whereas blood requirement was higher in the control group (1.68 ± 1 versus 0.52 ± 0.9 U of packed cells per patient, p < 0.001). The percent of patients exposed to blood products was significantly less in the TA group (36% versus 100%, p < 0.001). Fibrinogen split products were lower in the TA group during bypass (p < 0.001). Fibrinogen levels fell in both groups during cardiopulmonary bypass. Platelet number and function were reduced equally in both groups by cardiopulmonary bypass. Other test results were not different between groups. Conclusions. The use of low-dose TA during coronary artery bypass grafting significantly reduced the coagulopathy-induced postoperative bleeding and allogeneic blood products requirement. The low levels of fibrinogen split products during bypass in the study group reflect the inhibiting effect of TA in fibrinolysis. Tranexamic acid had no effect on platelet function during cardiopulmonary bypass.