Acute cholangitis is an infection of the bile and biliary tract which in most cases is the consequence of biliary tract obstruction. The two main causes are choledocholithiasis and neoplasia. Clinical diagnosis relies on Charcot's triad (pain, fever, jaundice) but the insufficient sensitivity of the latter led to the introduction in 2007 of a new score validated by the Tokyo Guidelines, which includes biological and radiological data. In case of clinical suspicion, abdominal ultrasound quickly explores the biliary tract, but its diagnostic capacities are poor, especially in case of non-gallstone obstruction, as opposed to magnetic resonance cholangiopancreatography and endoscopic ultrasound, of which the diagnostic capacities are excellent. CT scan is more widely available, with intermediate diagnostic capacities. Bacteriological sampling through blood cultures (positive in 40% of cases) and bile cultures is essential. A wide variety of bacteria are involved, but the main pathogens having been found are Escherichia coli and Klebsiella spp., justifying first-line antimicrobial therapy by a third-generation cephalosporin. Systematic coverage of Enterococcus spp. and anaerobic infections remains debated, and is usually recommended, in case of severity criteria for Enterococcus severity levels, or anaerobic bilio-digestive anastomosis for anaerobes. Presence of a biliary stent is the only identified risk-factor associated with infections by multidrug-resistant pathogens. Along with antimicrobial therapy, endoscopic or radiological biliary drainage is a crucial management component. Despite improved management, mortality in cases of acute cholangitis remains approximately 5%.