In rheumatoid arthritis (RA) there is increased risk of myocardial infarction and other cardiovascular diseases. In active process of RA one can find activation of hemostatic and fibrinolytic system and partialy this can explain more frequent cardiovascular complications. Generally, the whole-body cryotherapy, thought to be safe method in treating RA patients, can potentially change unstable balance in coagulation system. We measured some factors of hemostatic and fibrinolytic system in 46 RA patients and 20 OA patients treated in cryogenic chamber during 10 sesions (in temperature &#8211;120°C for 3 min). We found no inhibition of acute phase reactants in RA patients &#8211; there was no changes in serum CRP concentration. On the contrary, we found changes in the fibrinolytic system &#8211; i.e. lowering of t-PA antigen level in blood and increasing of PAP complexes concentrations (p < 0.05) in blood of RA patients. Lowering of t-PA antigen level and increasing of PAI-1 concentrations (p < 0.05) were seen after 10 sesions of cryotherapy in a group of OA patients. Despite the fact that there was no clinical adverse event observed, we conclude that the therapy of RA patients in cryogenic chamber can disturb hemostatic-fibrinolytic balance and in some patients may lead to thrombosis and cardiovascular events.