The general objective assigned to the European DIALysis (EUDIAL) Working Group by the European Renal Association – European Dialysis and Transplant Association (ERA-EDTA) was to enhance the quality of dialysis therapies in Europe in the broadest possible sense. Given the increasing interest in convective therapies, the Working Group has started by focusing on hemodiafiltration (HDF) therapies. A EUDIAL consensus conference was held in Paris on 13 October 2011 to discuss definitions, safety standards, clinical outcome and educational issues. Recently, the first report of the EUDIAL group was published, revisiting the definition, dose quantification, and safety of HDF. Since the meeting in Paris, new evidence has become available regarding the clinical benefits of HDF. This is the second report of the expert group in which the relation between HDF and clinical outcomes is systematically reviewed and analyzed, with emphasis on the relation between achieved convection volume and treatment effect.