A kinetic evaluation of dialytic methods using a diffusive-convective mechanism in comparison to the standard bicarbonate dialysis was performed in order to verify the possible therapeutic uses. The "kinetic" comparison of PFD and HDF to HBD, using equal quantities of dialysate, showed no significant change in the mention of uremic toxins of small molecular weight and a more efficient capacity to extract beta 2M by the diffusive-convective methods. The biophysical evaluation of dialysis still appears to represent the best means of defining the clearance possibilities and of identifying the most suitable technique for achieving a dialytic adequacy.