ABSTRACT— In experimental liver failure (pigs with totally devascularized liver) the effect of different types of extracorporeal hepatic assistance was evaluated. Group I (N = 6) were untreated controls, Group II (N = 6), simple cross-circulation, Group III (N = 6), cross-circulation with inflow in the donor directly into the portal vein and Group IV (N = 4), cross-perfusion with isolated perfused liver. The cross-circulation was started 20 h after devascularization. There was no change in survival time. Bilirubin was decreased by a factor of 2 and the prothrombin index increased by a factor of 2 after initiation of the cross-circulation due to the dilution. In contrast to this, ammonia was unchanged. During the perfusion no significant changes were found. In Group V (N = 4), extended cross-perfusion with isolated perfused liver for 20 h, starting just after exclusion of liver function in the recipient and with a new liver in the perfusion system every 6th hour, the survival time was significantly increased. Furthermore, changes in the biochemical variables were prevented. It is concluded that with a supply of quantitatively sufficient hepatic assistance it is possible to extend the survival time in experimental liver failure.