BACKGROUND: Major spine surgery can be associated with dramatic blood loss, thereby requiring a high-volume transfusion. Tranexamic acid inhibits fibrinolysis and it has been used in general surgery. The effect of tranexamic acid on blood loss and transfusion requirements during spine surgery was prospectively studied. METHODS: Twenty-two patients scheduled for orthopaedic surgery for spinal stenosis under general anesthesia were randomly selected to receive, either tranexamic acid administered as a bolus of 15 mg/kg, or the equivalent volume of saline, during the operation and postoperatively. The anesthetic and perioperative management were standardized. The total blood loss of each patient and transfusion requirements were noted. Hematocrit, PT, PTT, and platelet count measure were performed before and after surgery. RESULTS: The tranexamic acid group demonstrated a significantly less amount of blood loss (859.5 +/- 280.0 ml) compared to the placebo group (1366.0 +/- 333.7 ml). In addition the fluid and homologous transfusion requirements in the placebo group were greater than in the tranexamic acid group. CONCLSIONS: Tranexamic acid during major spine surgery significantly reduces both blood loss and consequent blood transfusion requirements.