We investigated the systemic effect of intraperitoneal low-molecular-weight heparin (LMWH) in continuous ambulatory peritoneal dialysis (CAPD) patients by measuring plasma total tissue factor pathway inhibitor (TFPI) levels, regarding the fact that the levels of plasma TFPI increases 2- to 4-fold after subcutaneous and intravenous administration of unfractioned heparin or LMWH. Eleven men and 6 women who had been on CAPD for 32 ± 26 months and 15 healthy controls were included in the study. After administration of intraperitoneal enoksiparin in dialysate, plasma samples were obtained 4 h later. TFPI levels were significantly higher in CAPD patients (207.8 ± 55 ng/ml) compared to the healthy subjects (72.5 ± 29 ng/ml) (p < 0.0001). Both TFPI levels (225.9 ± 47 vs. 207.8 ± 55 ng/ml) (p < 0.54) and plasma factor Xa (anti-FXa assay) (0.097 ± 0.14 vs. 0.093 ± 0.16 U/ml) (p < 0.54) levels did not show any statistical difference before and after intraperitoneal administration of LMWH. By these findings we might suggest that intraperitoneal LMWH does not have any systemic effect.