Endotoxin contributes to cholangitis. We measured concentrations of bile and serum endotoxin and serum cytokines after biliary drainage for obstructive jaundice with or without acute cholangitis. Patients who underwent percutaneous transhepatic cholangiodrainage (PTCD) in 1995 were classified as having acute cholangitis (group A; n = 11), having a history of acute cholangitis (group B; n = 5), or not having a history of acute cholangitis (group C; n = 13). Bile endotoxin was positive (above the cut-off value) in all patients in groups A and B, and in five patients in group C. The mean concentration of bile endotoxin was significantly higher in groups A and B than in group C. After PTCD, the bile endotoxin level decreased more slowly in group A than in the other groups. Before PTCD, the mean serum levels of IL-1 receptor antagonist (IL-1ra), IL-6, and IL-8 were higher in group A than the other groups. The serum levels of IL-1ra and IL-6 before PTCD were significantly higher when the acute cholangitis was more severe. The mean serum levels of cytokines increased just after PTCD and then decreased. In group A, the serum level of IL-6 at 5 h after PTCD was significantly correlated to the endotoxin level in bile at this time. Increases in cytokines may participate in the pathophysiological changes of acute cholangitis. Biliary drainage for acute cholangitis causes improvement by decreasing the bile endotoxin level addition to decreasing bile-duct pressure, thereby preventing excess production of inflammatory cytokines.