PURPOSE OF THE STUDY Tranexamic acid as a haemostatic agent is commonly used in multiple medical branches. Over the last decade, there has been a steep rise in the number of studies evaluating its effect, i.e. blood loss reduction in specific surgical procedures. The aim of our study was to evaluate the effect of tranexamic acid on reducing intraoperative blood loss, postoperative blood loss into the drain, total blood loss, transfusion requirements, and development of symptomatic wound hematoma in conventional single-level lumbar decompression and stabilization. MATERIAL AND METHODS The study included patients who had undergone a traditional open lumbar spine surgery in the form of single-level decompression and stabilisation. The patients were randomized into two groups. The study group received a 15 mg/kg dose of tranexamic acid intravenously during the induction of anaesthesia and then again 6 hours later. No tranexamic acid was administered to the control group. In all patients, intraoperative blood loss, postoperative blood loss into the drain, and therefore also total blood loss, transfusion requirements and potential development of a symptomatic postoperative wound hematoma requiring surgical evacuation were recorded. The data of the two groups were compared. RESULTS The cohort includes 162 patients, 81 in the study group and the same number in the control group. In the intraoperative blood loss assessment, no statistically significant difference between the two groups was observed; 430 (190-910) mL vs. 435 (200-900) mL. In case of post-operative drain blood loss, a statistically significantly lower volume was reported after the tranexamic acid administration; 405 (180-750) mL vs. 490 (210-820) mL. When evaluating the total blood loss, a statistically significant difference was also confirmed, namely in favour of the tranexamic acid; 860 (470-1410) mL vs. 910 (500- 1420) mL. The reduction of total blood loss did not result in a difference in the number of administered transfusions; transfusions were given to 4 patients in each group. A postoperative wound hematoma requiring surgical evacuation developed in 1 patient in the group with the tranexamic acid and in 4 patients in the control group, but the difference was not statistically significant with respect to the insufficient group size. No patient in our study experienced complications associated with tranexamic acid application. DISCUSSION The beneficial effect of tranexamic acid on reducing blood loss in lumbar spine surgeries has already been confirmed by numerous meta-analyses. The question remains in what types of procedures, at what dose and route of administration its effect is significant. To date, most of the studies have explored its effect in multi-level decompressions and stabilizations. Raksakietisak et al., for instance, report significant reduction in total blood loss from 900 (160, 4150) mL to 600 (200, 4750) mL following an intravenous injection of 2 bolus doses of 15 mg/kg tranexamic acid. In less extensive spinal surgeries, the effect of tranexamic acid may not be that distinct. In our study of single-level decompressions and stabilizations, no reduction in the actual intraoperative bleeding was confirmed at the given dosage. Its effect was seen only in the postoperative period in a significant reduction of blood loss into the drain, thus also in the total blood loss, although the difference between 910 (500, 1420) mL and 860 (470, 1410) mL was not that significant. CONCLUSIONS By intravenous application of tranexamic acid in 2 bolus doses in single-level decompression and stabilization of the lumbar spine a statistically significant reduction in postoperative blood loss into the drain and also total blood loss was confirmed. The reduction in the actual intraoperative blood loss was not statistically significant. No difference was observed in the number of administered transfusions. Following the tranexamic acid administration, a lower number of postoperative symptomatic wound hematomas was recorded, but the difference was not statistically significant. Key words: tranexamic acid, spinal surgeries, blood loss, postoperative hematoma.