Biofiltration is a hemodiafiltration technique performed with a base-free dialysate and simultaneous infusion in postdilution mode of isotonic bicarbonate solution. This technique has the advantages without the inconveniences of bicarbonate dialysis that result from complicated hardware and the need of frequent trouble shooting. In biofiltration, 1) the sodium dialysate concentration should be monitored according to the patient's body weight gain and to the sodium concentration of infusion fluid to obtain adequate sodium mass balance and 2) plasma bicarbonate is easily controlled because the final plasma bicarbonate concentration depends upon the bicarbonate infusion flow rate. Long-term follow-up evaluation (6-24 months) of 76 patients on a dialysis strategy of 3 hr three times a week from 17 European dialysis centers has shown that biofiltration is a simple and safe alternative to bicarbonate dialysis. It could be the way to fulfill the requirements of short time/high quality dialysis, which seems to be the developing trend of dialysis in the future. These advantages are, however, balanced by the extra cost of high flux dialyzers and infusion fluid.