Objective To evaluate the effect of a bioartificial liver (BAL) system for treatment of acute liver failure (ALF) in canines and its relationship to serum endotoxin. Methods ALF was induced by end-side portocaval shunt combined with common bile duct ligation and transection. Ten ALF canines were distributed to BAL group (n=5), or to a control group (n=5). Each BAL circulation lasted 5h. Serum endotoxin, alanine aminotransferase (ALT) and total bilirubin (TB) before establishment of ALF model, pre-circulation and post-circulation were determined. Results Serum endotoxin level was 0.284 EU/ml, 0.526 EU/ml and 0.416 EU/ml before establishment of ALF model, and pre-circulation and post-circulation in BAL group, respectively. The serum endotoxin level in BAL group increased pre-circulation (P