The Tokyo Guidelines formulate clinical guidance for healthcare providers regarding the diagnosis, severity assessment, and treatment of acute cholangitis and acute cholecystitis. The Guidelines were developed through a comprehensive literature search and selection of evidence. Recommendations were based on the strength and quality of evidence. Expert consensus opinion was used to enhance or formulate important areas where data were insufficient. A working group, composed of gastroenterologists and surgeons with expertise in biliary tract surgery, supplemented with physicians in critical care medicine, epidemiology, and laboratory medicine, was selected to formulate draft guidelines. Several other groups (including members of the Japanese Society for Abdominal Emergency Medicine, the Japan Biliary Association, and the Japanese Society of Hepato-Biliary-Pancreatic Surgery) have reviewed and revised the draft guidelines. To build a global consensus on the management of acute biliary infection, an international expert panel, representing experts in this area, was established. Between April 1 and 2, 2006, an International Consensus Meeting on acute biliary infections was held in Tokyo. A consensus was determined based on best available scientific evidence and discussion by the panel of experts. This report describes the highlights of the Tokyo International Consensus Meeting in 2006. Some important areas focused on at the meeting include proposals for internationally accepted diagnostic criteria and severity assessment for both clinical and research purposes.