Hyperleptinemia is also common in chronic renal failure, particularly in CAPD. On the other hand, cardiovascular events related to thrombosis are a predominant cause of death and account also for an important morbidity in uremic patients. Treatment with recombinant human erythropoietin (rHuEPO) may shift the precarious hemostatic balance towards thrombosis. Therefore, the aim of the study was to assess the relationships between leptin and platelet aggregation and some hemostatic parameters in CAPD patients treated with rHuEPO. The study was performed on 15 patients maintained on CAPD given rHuEPO and 13 subjects without rHuEPO therapy served as a control group. Platelet aggregation was studied in both platelet-rich plasma (PRP) and in the whole blood. Tissue factor (TF) and tissue factor pathway inhibitor (TFPI) (antigens and activities), von Willebrand factor, trombomodulin, protein C, thrombin activatable fibrinolysis inhibitor (TAFI) and leptin (serum and dialysate) were assayed by using commercially available kits. Patients in both groups studied did not differ significantly with respect to age, BMI, duration of renal replacement therapy, and other hematological and hemostatic parameters studied as well as leptin serum and dialysate leptin. In CAPD patients treated with rHuEPO serum and dialysate leptin significantly correlated with tissue factor pathway inhibitor, protein C, thrombomodulin, ristocetin-induced platelet aggregation in the whole blood and PRP. In CAPD patients not treated with rHuEPO the significant correlations were observed between serum and dialysate leptin and protein C. Positive correlations between platelet aggregation and leptinemia in CAPD patients might indicate that hyperleptinemia could be associated with the cardiovascular disease in dialyzed patients. Leptin might contribute at least in part to the thrombotic complications observed in CAPD patients.