Clinical course after the start of artificial liver support with on-line hemodiafiltration. After 10 on-line hemodiafiltration sessions, a 29-year-old man with acute hepatitis B virus infection (Case 14) experienced complete and rapid resolution of hepatic encephalopathy. Artificial liver support with on-line hemodiafiltration and plasma exchange maintained lucid consciousness and minimal coagulation function for 25 days during an aggressive treatment period. Prothronbin time deteriorated without the plasma exchange rapidly and it could not be maintained by 8 units drip infusion of fresh frozen plasma. Computerized tomography examination on 16th day revealed further progression of liver atrophy, liver transplantation was therefore recommended but he could not receive liver transplantation because of the lack of a living donor candidate. Then, the treatment was reduced, and discontinued on the 36th day. He died on the 42nd day. PE, plasma exchange; FFP, fresh frozen plasma; HDF, hemodiafiltration.