Objectives: Plasma exchange or dual-filtration plasmapheresis (DFPP) is used to remove anti-A/anti-B antibodies in ABO-incompatible kidney transplant recipients. However, the substitution fluid used for DFPP has a low osmotic pressure, which may cause a decrease in the blood pressure and discomfort due to a decrease in the circulating blood volume during treatment. The aim of the present study was to determine whether DFPP can be performed more safely by adding sodium chloride (NaCl) to the substitution fluid to avoid decrease of the circulating blood volume during treatment. Methods: The study was conducted in 32 patients who needed elimination of anti-A/anti-B antibodies prior to renal transplantation. The first DFPP was performed using 800 ml to 1 L of conventional substitution fluid (a mixture of lactic solution and 20% albumin solution) (control treatment). The second DFPP was performed with substitution fluid to which 20 ml of 10% NaCl had been added (NaCl treatment). Changes in the circulating blood volume (⊿BV) in both treatments were measured every 30 minutes.The blood osmolality and total protein (TP), sodium and hemoglobin (Hb) concentrations were also measured before and after the DFPP. Results: In the NaCl treatment, the osmolality of the substitution fluid increased from 194±12 to 266±18 mOsm. In addition, the ⊿BV was less pronounced from 120 to 210 minutes (P<0.01). The NaCl treatment prevented significant post-treatment plasma osmotic pressure decrease, TP decrease, and Hb increase observed in the control treatment; however, the plasma Na concentration did not change in either treatment. The NaCl treatment was associated with a less pronounced decrease of the blood pressure and less discomfort. Conclusions: Addition of NaCl to the substitution fluid prevented a significant drop in the circulating blood volume during DFPP.