72 patients scheduled for posterior lumbar interbody fusion were randomized to either high-dose tranexamic acid, low-dose tranexamic acid, or placebo saline. All patients were treated with an initial bolus prior to incision, followed by continuous infusion for the next 5 hours. Main outcome measures included intraoperative, postoperative, and total blood loss, as well as transfusion rate. Measures of blood loss volume all significantly favoured the high-dose TXA group compared to both the low-dose TXA group and saline group, though no patient in any of the three groups required transfusion. Two cases of venous thromboembolic complication were observed, both occurring in the placebo group.