We report in this study the outcome of chronically hemodialysed patients with a new technique: Acetate free biofiltration 84@1000. This study is divided into two steps: during the first period we studied the hemodynamic stability of the technique in patients hemodynamically unstable under bicarbonate hemodialysis. During the second period we compared the hemodynamic effects and the quality of dialysis in these patients with other patients under bicarbonate hemodialysis. We obtained less hypotensive episodes, a better correction of acidosis, a better tolerance of the technique and comfort of the patient with the new technique, the quality of dialysis was the same with both techniques. We recommend the use of acetate free biofiltration 84@1000 whenever the patients are hemodynamicallyunstable with bicarbonate hemodialysis.