Free light chain removal was compared in the polymethylmethacrylate (PMMA) membrane Filtryzer BK-F, the polyphenylene HFR17 filter and the conventional polysulfone filter F7 High Performance dialysers (HPS). Twenty chronic hemodialysis patients were enrolled. The patients were randomized into two groups of treatment lasting six weeks each. The dialysis sessions checked were the midweek sessions and the blood was drawn at times 0, 120' and 240'. Kappa (k) and lambda (l) light chain levels, beta2microglobulin (β2M), C reactive protein (CRP) and albumin were checked.