Blood purification, mainly plasma exchange (PE), was carried out for 13 cases of acute, and two cases of chronic postoperative liver failure. Four of thirteen acute cases (31%) survived. Although only one of eight with chronic liver disease survived, three of five without chronic liver disease survived. In most of those who lived, other organ failure occurred less often; total bilirubin and blood ammonia were less than 15 mg/dl and 200 micrograms/dl, respectively, before PE: and total bilirubin, blood ammonia, and branched chain amino acid/aromatic amino acid (BCAA/AAA) ratios recovered after five or fewer sessions of PE. Two chronic cases, treated for 1 and 4 years, respectively, were good candidates for liver or multiple organ transplantation. Although both died, PE was effective in reducing jaundice and in improving consciousness and general condition. Plasma exchange should be introduced early after assessing the changes in total bilirubin, blood ammonia, and coma grade in patients with acute postoperative liver failure. Plasma exchange could be useful as a chronic hepatic support system for those awaiting liver transplantation.