PUREMA H (referred to as PES) is an innovative dialysis membrane for enhanced low-molecular-weight (LMW) protein removal. The purpose of the study was to prove whether its efficacy in hemodialysis (HD) matches that of online hemodiafiltration (HDF) with conventional high-flux membranes. In a prospective, randomized, cross-over study on eight maintenance dialysis patients, treatment efficacy of HD with PES was compared with online postdilution HDF with the two synthetic high-flux membranes polysulfone (referred to as PSU) and Polyamix (referred to as POX). Apart from the infusion of replacement fluid, which was set at 20% of the blood flow rate of 300 mL/min, operating conditions in HD and HDF were kept identical. Small solute and LMW protein plasma clearances as well as the reduction ratio (RR) of cystatin C and retinol-binding protein were not different between the therapies. HDF with POX resulted in a significantly lower myoglobin RR as compared with HD with PES, and HDF with PSU. A 4% higher beta(2)-microglobulin RR was determined in HDF with PSU (73 +/- 5%) as compared with PES in HD (69 +/- 5%). The albumin loss was below 1 g for all treatments. Despite the fact that simple HD did not fully exploit the characteristics of PES, it achieved essentially similar LMW protein removal and albumin loss as compared with online postdilution HDF with the conventional synthetic high-flux membranes PSU and POX. Therefore, HD with PES may have beneficial effects on the outcome of maintenance dialysis patients similar to high-efficiency HDF.