Lactic acidosis is often associated with a strikingly high mortality. The effective therapy involves treatment of the underlying cause and correction of acidemia by infusion of sodium bicarbonate. When lactic acidosis is accompanied by oliguric renal failure, bicarbonate therapy becomes more complex with volume overload and hypernatremia. Hemodialysis against a bicarbonate-buffered dialysate will achieve this. However, it is generally tolerated poorly by hemodynamically unstable patients. We report here three hemodynamically unstable patients with severe lactic acidosis, which was treated successfully by the use of continuous venovenous hemodiafiltration with bicarbonate based dialysate and replacement solution. We would suggest that continuous renal replacement with bicarbonate buffer should be indicated in the treatment of severe lactic acidosis.