The aim of the work was to evaluate the von Willebrand factor antigen (vWF Ag) concentration in the blood plasma of hemodialysed patients with chronic renal failure. The study was performed in the group of 43 patients (means aged 42.8 years) with chronic renal failure dialysed means 4 hours 3 times a week. The blood was obtained before and after hemodialyze and in 11 patients additionally after 1 year of systematic hemodialyze. The control group consisted of 51 healthy volunteers means aged 35.6 years. In the citric blood plasma concentration of vWF Ag was determined using immunosorbed enzyme-linked assay (ELISA). In the blood plasma of patients with chronic renal failure significantly higher concentration of vWF Ag than in controls was observed. 4-hours and 1-year dialyze did not influence the level of vWF Ag in patients with chronic renal failure.