The aim of the study was the evaluation of the participation of fibrinolytic system in the pathogenesis of haemostasis disturbances on the base of the determination of plasminogenesis intensity and some other fibrinolytic parameters. The study was performed in the group of 73 patients suffering from chronic meyloproliferative syndromes aged 36-78 (means 54,0) years: in 22 with chronic myelogenous leukemia (CML), in 25 with polycythemia vera (PV), in 21 with essential thrombocythemia (ET) and in 5 patients with meylofibrosis (MF). Control group contained 30 healthy volunteers sex and age matched. In the citric plasma obtained from venous blood concentration of plasmin-alpha2 antiplasmin complexes (PAP) using immunosorbed method (ELISA), alpha-2-antiplasmin with chromogenic method, concentration of fibrinogen and fibrin/ /fibrinogen degradation products (FDP) were determined. In blood plasma of patients with chronic myeloproliferative syndromes increased concentration of PAP complexes was detected what is the evidence of high intensity of plasmin generation.