Functional disturbances among different tissues and organic systems are associated with chronic renal failure. The most common problems following the disturbances in complex hemostatic changes in uremic patients are prolonged bleeding time ant the increased thrombosis tendency. As the patients vascular access is critical to the treatment of the chronic haemodialysis patient, we performed an investigation of causes of repeated vascular access thrombosis with purpose of detecting any consistent abnormality of the haemostatic system. Research has been conducted on a group of 29 patients (14 males and 15 females), age 21 to 61 (x = 45), on regular haemodialysis from 1 to 6 years (x = 2.2); 23 of them having one episode of thrombosis of vascular access, and 6 having two episodes. Partial thromboplastin time was among the normal ranges in all investigated subjects, three of them had low prothrombine time and thrombine time was prolonged in two cases. The high fibrinogen value was found in 19 patients. Mean value of platelet count was normal, though seven patients had thrombocytopenia. Absence of coagulum retraction was found in three patients. Assessment of blood coagulation in this study could not explain the development of repeated thrombotic events affecting arterio-vein fistula in chronic renal failure patients receiving haemodialysis. That points out the necessity to analyze functional status of natural coagulation inhibitors, fibrinolytic system and platelet function.