Recent in vitro and clinical evidence suggest that protein-bound uremic retention solutes contribute substantially to the pathophysiology of the uremic syndrome. As compared to their water-soluble counterparts however, the removal of these molecules by conventional dialysis techniques is limited. It was the purpose of the present paper to review the existing data on the dialytic removal of protein-bound solutes and on the potential advantages of newly developed epuration techniques. Furthermore, the toxicity profile of this group of molecules is discussed.