Abstract <p>The review presents the results of studying the hemocoagulation system in Soviet and Russian experiments that simulate the influence of spaceflight factors on the human body. Head-down bed rest and immersion are recognized as the most adequate models of microgravity. The effects of overloads were simulated by rotation on a centrifuge. In the dynamics of experiments with bed rest, multidirectional changes in the activity of the procoagulant, anticoagulant, and fibrinolytic components of hemostasis were observed, the state of which depended on the duration of exposure to limited physical activity. Under immersion conditions, the researchers observed an increase in the procoagulant activity and a decrease in the fibrinolytic activity with multidirectional changes in the anticoagulant potential of the blood. According to some studies, exposure to hypergravity leads to an increased anticoagulant and fibrinolytic activity against a background of hypocoagulation, while others suggest hypercoagulation accompanied by the activation of fibrinolysis. The combination of gravitational loads and unloading, according to researchers, leads to a decrease in the procoagulant activity and an increase in the fibrinolytic activity. The differences between the post-flight data and the results of model experiments are determined by the impossibility of reproducing the effect of the entire complex of spaceflight factors on the human body under terrestrial conditions.</p>