Background. Low-molecular weight heparins (LMWH) are safe, their effect is comparable with that of unfractionated heparin (UFH) and they are much more convenient in practice. Methods. 60 stable chronic HD patients were included in the study. Trombotic and hemorrhagic complications were accessed during a single HD procedure. Then thirty patients were randomly assigned to either low molecular weight heparin (1 mg/kg body weight) or standard heparin regime of anticoagulation and followed prospectively for 24 weeks. Parameters of hemostasis were measured before and after the first post-randomization HD procedure, then in 1, 3 and 6 months. Conclusions. In spite of an adequate UFH anticoagulation therapy during the HD procedure patients have intravascular hypercoagulation that cannot be revealed by conventional coagualologic methods. As for the clinical signs of thrombophilia, the anticoagulative effect of Enoxaparin (Clexane) during the HD treatment is comparable to that with standard heparin. Enoxaparin has a higher efficiency on intravascular hypercoagulation in patients on program HD than in those treated with UFH.