['Vascular access failure is a common cause of morbidity in patients with end-stage renal failure on hemodialysis (HD). Activation of the coagulation system and formation of a thrombus play important roles in recurrent arteriovenous fistula/graft (AVFG) failure. Thrombin in complex with thrombomodulin (TM) activates the anticoagulant protein C and creates activated protein C (APC), which is subsequently inactivated by the protein C inhibitor (PCI). The plasma concentration of the complex between APC and PCI (P-APC-PCI complex) is increased in hypercoagulable states and is therefore a sensitive indicator of the degree of activation of blood coagulation.', 'Thirty-five HD patients dialyzed through a functioning AVFG were studied. The period of patency of AVFGs was recorded. Blood was drawn before and after the HD session for the analysis of the APC-PCI complex, soluble TM concentration and activity, von Willebrand factor antigen and homocysteine.', 'Patients with frequent AVFG failures (n = 8) had a significantly lower level of P-APC-PCI complex (median 0.09 microg/l) than those with less frequent AVFG failures (median 0.18 microg/l; n = 27; p = 0.04). No other significant differences were found between the groups.'] Is low plasma activated protein C-protein C inhibitor complex concentration associated with vascular access failure in hemodialysis patients?