Chelidonium majus is a well-known source of biologically active compounds. Most of them are alkaloids, which are used in researches and for tradition medicine. In this study, we explored the influence of C. majus crude total extract onto blood coagulation system in vitro, primary and secondary hemostasis. Aim. To study influence of C. majus extract onto blood coagulation process. Methods. Turbidimetry of blood plasma, APTT test with chromogenic substrates, and platelet aggregation were used in the work. Results. We demonstrated moderate stimulating effect of the extract on platelets (the rate of platelet aggregation increased up to 10%, followed by disaggregation). Extract also increased the rate of platelet aggregation stimulated by 12.5 mcM of ADP. We observed the increase in the plasma clotting time in the presence of the extract, that corresponded to the 274, 411, 685, 1370 mcg of dry extract, from 70 s in control to 80, 90, 170 and 180 s, respectively, in turbidimetry test of plasma stimulated by APTT-reagent. However, APTT test with the chromogenic substrate of thrombin (S2238) did not show significant influence of this plant’s extract on thrombin activity. Conclusions. Thus, we can conclude that anticoagulant activity of Chelidonium majus extract corresponded to the direct inhibition of fibrin polymerization.