Eight volunteered male test-subjects (20-40 y.o.) took part in an experiment with 21-hr bed rest aimed to investigate trends in the hemostasis parameters (activated partial thromboplastin time, prothrombin time, thrombin time, fibrinogen, plasminogen, D-dimers, soluble fibrin-monomer complexes (SFMC), as well as antithrombin III (ATIII) and protein C (antiplasmin) activities) after diuretics-induced dehydration followed by intravenous infusion of colloid and crystalloid solutions. It was shown that noncompensible dehydration during bed rest does not lead to noteworthy alterations in the procoagulating component of hemostasis. Intravenous infusion of blood substituting sterofundin (crystalloid) and venofundin (colloid) to the bedrested human subjects accelerated coagulation within the physiological norm. In all series of the experiment ATIII was suppressed and plasminogen content went down causing growth in SFMC. Fibrinogen concentration remained essentially unchanged pointing to the absence of acute reaction of organism to the experimental conditions.