Acute cholangitis is a clinical syndrome marked by fever, jaundice, and abdominal pain that develops because of stasis and infection in the biliary tract. Patients with cholangitis may present with symptoms ranging from a mild, recurrent illness to overwhelming sepsis. Increased age, malignant obstruction, and a rapidly progressive, systemic illness define a group of patients at increased risk. Patients who are delayed in diagnosis, present with septicemia, or fail to respond to conservative treatment still have substantial morbidity and death from cholangitis. Antibiotic therapy that includes coverage for anaerobes and gram-negative, enteric organisms together with other supportive measures often resolves the acute episode, permitting elective diagnostic procedures prior to definitive treatment of biliary tract obstruction. Advances in endoscopic and transhepatic procedures have reduced the necessity for and risks associated with emergent operative biliary drainage.