Objective of the study was to investigate the effect of Mexidol on the fibrinolytic activity of Actilyse, Metalyse and Fortelyzin. Material and methods. The study was performed in vitro on blood clots obtained from the blood of wistar rats and healthy donor. The blood clots were incubated with blood plasma for 3 hours at 37 °C to wich Mexidol (0.1, 1, 10 μg/ml), thrombolytics Actilyse (15, 2, 0.5 μg/ml), Metalyse (10, 1, 0.1 μg/ml), Fortelyzin (5, 1.5 and 0.5 μg/ml) or a combination of an antioxidant and thrombolytics were added. To assess the effectiveness of thrombolysis, the % change in blood clotss mass was analyzed, as well as the level of D-dimer in the blood plasma after the end of incubation, which was analyzed by ELISA. Results. Mexidol in all tested concentrations of 0.1—10 μg/ml did not affect the blood clots mass and D-dimer level. Actilyse in concentrations of 15 and 2 μg/ml caused a decrease in blood clots mass by 27.68±9.45% (p<0.0001) and by 15.72±4.38% (p=0.0011), and a concentration of 15 μg/ml also increased the D-dimer concentration compared to the control by 70.9% (p=0.055). Metalyse at a concentration of 10 μg/ml caused a decrease in blood clots mass by 22.53±2.83% (p<0.0001), at a concentration of 1 μg/ml — by 9.57±2.31% (p<0.0001), at a concentration of 0.1 μg/ml — by 3.76±1.04% (p=0.0115). At a concentration of 10 μg/ml, metalyse also caused an increase in the concentration of D-dimer compared to the control by 37.4% (p=0.0022). The combination of actilyse and metalyse with Mexidol in all tested concentrations did not have a reliable effect on the effectiveness of thrombolytics. Fortelyzin in all concentrations did not cause lysis of blood clots obtained from rat blood, but at a concentration of 5 μg/ml it caused a decrease in the mass of blood clots from human blood by 39.69±15.97% (p<0.001), at a concentration of 1.5 μg/ml — by 33.12±2.48% (p=0.001), and at a concentration of 0.5 μg/ml — by 17.79±5.24% (p=0.078). Mexidol in all tested concentrations did not affect the effectiveness of the thrombolytic. Conclusion. The obtained results indicate that Mexidol does not affect the fibrinolytic activity of Actilyse, Metalyse and Fortelyzin.