Aim. To study dynamics of laboratory characteristics of plasma hemostasis in the patients presenting with idiopathic deep venous thrombosis of the lower extremities and receiving anticoagulant therapy. Material and methods. The present prospective study involved 37 patients (17 women and 20 men) at the age of 57.4±13.6 years presenting with deep venous thrombosis in the absence of the signs of pulmonary embolism or oncological diseases at the onset of the treatment. Anticoagulant therapy was conducted using unfractionated heparin based on the standard scheme. The laboratory studies of the hemostatic system included determination of the generally used parameters, such as activated partial thromboplastin time, fibrinogen and prothrombin levels, international normalized ratio, and prothrombin index. In addition, the "Thrombodynamics" test was performed to measure the stationary clot growth rate (Vst). The results of anticoagulant therapy were assessed from the dynamics of clinical signs and symptoms and ultrasound angioscanning taking into account dynamics of laboratory parameters of plasma hemostasis. The favourable outcome of the treatment was documented in 32 (86.5%) patients who were discharged for further outpatient therapy with the use of warfarin at a dose chosen on an individual basis. Five (13.5%) patients suffered either deterioration of clinical condition and/or negative dynamics of the results of ultrasound angioscanning; they were referred to a specialized vascular clinic. The present study has demonstrated that anticoagulant therapy with the use of unfractionated heparins followed by warfarin treatment allows in the majority of cases to obtain hypocoagulation confirmed by laboratory studies in conjunction with the clinically and ultrasonically apparent improvement of clinical condition. The results of the "Thrombodynamics" test in combination with standard laboratory tests for monitoring plasma hemostasis provide reliable information on the state of the hemostatic system and permit to distinguish the patients in need of additional anticoagulant therapy to be prescribed on an individual basis. The absence of hemorrhagic complications suggests the sufficiently high level of safety of anticoagulant therapy.