Materials and methods: a prospective non-randomized pilot multicenter study of the informative-ness and clinical significance of hemostasis laboratory tests in 1210 patients with COVID-19 in disease course, including favorable and unfavorable outcomes, was performed. Hemostasis was assessed using clotting tests and D-dimer concentration, thromboelastography (TEG) and thrombodynamics (TD). Results: comparison of COVID-19 laboratory parameters and clinical picture showed that 75% of patients have pronounced activation of the plasma coagulation system upon admission to the hospital. Hypercoagulation is recorded in all tests, reaching a maximum in patients with subtotal (CT-3) and total (CT-4) lung lesion and/or resuscitation patients with a clinical picture of pulmonary embolism and unfavorable outcome. Low molecular weight heparins (LMWH) in a standard dosage leads to suppression of the initial hypercoagulable syndrome in more than half of the patients (from 75 to 31%). All patients without LMWH laboratory effect developed thrombotic complications. For clotting tests, insufficient sensitivity to changes in hemostasis against the background of LMWH was revealed. The D-dimer test effectively correlates with the severity and outcomes of COVID-19, but is not suitable for the control of heparin therapy, which is associated with the effect of lysis of existing blood clots and the lack of response to a decrease in the coagulation activity of patients. Methods of thromboelastography and thrombodynamics effectively record a decrease in the activity of the coagulation system and can be used to control heparin therapy. The correlation coefficient between the methods was 0,77. The dynamic indices of D-dimers, TEG and TD in severe patients and, especially, in patients with fatal outcomes revealed the greatest sensitivity to the control of heparin therapy in the Thrombodynamics test, which allows, along with thrombosis, to record hypercoagulable states and the risk of bleeding, which are the outcome of thrombohemorrhagic syndrome in patients with COVID-19. © 2020, Pediatria Ltd. All rights reserved.