BACKGROUND: Acute Obstructive Septic Cholangitis (AOSC) is a serious infectious disease of the biliary system. It is prone to develop into septic shock without prompt management. METHODS: Bile was collected from 71 AOSC patients (45 AOSC without septic shock, 26 AOSC with septic shock) during biliary drainage and on days 1 and 3 postoperatively. The levels of High Mobility Group Protein 1 (HMGB1), Interleukin (IL)-1, IL-6, and Tumor Necrosis Factor alpha (TNF-α) were measured. The differences in the levels of biliary factors and their correlation with clinical biochemical indicators were assessed in the two groups. RESULTS: HMGB1 gradually decreased in both groups in the postoperative period. Intraoperative levels of biliary HMGB1 were significantly higher in patients with AOSC with septic shock. TNF-α and HMGB1 decreased slowly in patients with AOSC with septic shock on postoperative days 1 and 3, and the levels of the factors decreased less. Biliary HMGB1 levels were negatively correlated with white blood cell count and positively correlated with blood urea nitrogen, blood creatinine, procalcitonin, and C-reactive protein. A bile HMGB1 level of 1108.3 pg/mL was the cut-off value to differentiate patients with AOSC with or without septic shock. CONCLUSION: Biliary HMGB1 levels are elevated in patients with AOSC with septic shock and decrease slowly in the postoperative period. This suggests that HMGB1 is of considerable importance as a potential therapeutic target in the pathogenesis of septic shock in AOSC patients.