Aim. The objective of the present study was to estimate the effectiveness and safety of warfarin therapy in the patients treated with this agent after deep venous thrombosis and included in the system of centralized monitoring the international normalized ratio (INR). Material and methods. The analysis of the results of INR determination involved 118 patients treated with warfarin after deep venous thrombosis and included in the system of centralized INF monitoring. The effectiveness of control was estimated by the Rosendaal method. Results. Mean time during which the therapeutic INR range was maintained in the patients throughout the study period was at least 70% of the total. A single (0.8%) case of severe hemorrhage (hematoma of the tongue and the floor of the mouth) was documented. Six (5.08%) patients presented with minor bleeding. None of the patients developed a relapse of deep venous thrombosis. Conclusion. The introduction of the system of centralized INF monitoring made it possible to significantly improve the quality of the prolonged prophylactic treatment of deep venous thrombosis at the level of district health services. The use of this system permits to overcome skepticism of physicians as regards warfarin therapy safety.