Objective. To determine the most informative TEG parameters characterizing coagulation disturbance caused by dilutional thrombocytopenia and hypofibrinogenemia. Material and methods. TEG parameters in 16 healthy volunteers (in vitro) were tested at the 1st stage of research in order to analyze the influence of thrombocytes on clot formation. Their plasma consisted of normal cellular (thrombocytes) and humoral coagulation factors was diluted with platelet-poor plasma collected from the same donors after double centrifugation. At the 2nd stage, 20 patients with over 1,5-liter blood loss were analyzed to investigate dilution influence on hemostasis. Serum fibrinogen, thrombocytes count and TEG parameters have been measured within 2 hours after the onset of 2.5-liter infusion therapy and again after 24 hours. Results. MA amplitude and α angle were the most sensitive parameters. Their changes in vitro were shown in healthy volunteers when thrombocyte count falls below 50·109. In patients with severe blood loss, a 2-fold decrease of fibrinogen was observed within 2 hours after the onset of infusion therapy. This tendency was accompanied by reduced MA amplitude and α angle in platelet-poor plasma. Conclusion. The absence of significant changes of MA amplitude and α angle confirms the key role of cellular part in sustainable hemostasis despite a 2-fold decrease of fibrinogen level.