 As the accumulation of MMW substances has been implicated in increased oxidative stress and endothelial dysfunction, a reduction of these compounds might improve these derangements. In addition, cardiac dysfunction, atherosclerosis as measured by left ventricular mass index LVMi, carotid intima media thickness CIMT and vascular stiffness as measured by pulse wave velocity PWV might be reduced during HDF, as compared to low-flux HD. 