AbstractComparative study of the clinical features of 125 cases of acute cholangitis revealed that acute obstructive suppurative cholangitis (AOSC, 19 cases) was characterized by leukocytosis, high transaminase levels, bilirubinemia, and a marked thrombocytopenia. Most species of bacilli isolated from the purulent bile were gram‐negative and in 9 of 12 cases of AOSC that we checked, the same species were found in the blood as in the bile. In 12 of the 19 cases of AOSC, plasma endotoxin levels were assayed by theLimulus test and found to be elevated. Of the 22 cases of cholangitis other than AOSC, only 5 showed transitory positive results. Laparotomy decompression of the bile duct in 8 patients with AOSC resulted in 4 deaths from post‐operative complications. However, 7 of the 11 patients placed on emergency percutaneous transhepatic cholangio‐drainage (PTCD) recovered from shock and underwent successful surgery later. We confirmed in an experimental study the initiation of cholangiovenous reflux in mongrel dogs. The cholangiovenous reflux of bacteria or endotoxin seems to induce the state of shock in patients with AOSC. In conclusion, we recommend that emergency decompression of the biliary tract even for AOSC patients in shock be performed by a procedure less risky than laparotomy, such as PTCD.