Cholangitis results from the combination of bactibilia and biliary tract obstruction. In recent years considerable progress has been made in the diagnosis and treatment of cholangitis; advances in endoscopic techniques and antibiotic therapy have ameliorated the prognosis of cholangitis. The choice of an antimicrobial regimen for cholangitis should take into account the antibiotic sensitivities of bacteria colonizing biliary tree, the antibiotic excretion into bile and whether biliary obstruction or bacteremia is present. Successful treatment depends on relieving biliary obstruction and administering antibiotics effective against bacteria implicated. The initial therapy should be active against E. coli and Klebsiella spp., while it is controversial whether the empirical antibiotic regimen should also include coverage against Enterococcus, Pseudomonas and anaerobes. The ureidopenicillins are the preferred initial treatment; the combination piperacillin-tazobactam may be active against the resistant species. Second generation cephalosporins like cefamandole and cefoxitin are still useful, cefoperazone gives excellent coverage against gram-negative bacteria, while cefepime may be suitable as treatment for acute cholangitis. In severe cholangitis an aminoglycoside can be added to the beta-lactamin; once-daily aminoglycoside administration is associated with a reduced incidence of nephrotoxicity also in patients with cholestasis. Whether the fluoroquinolones are effective in treatment for cholangitis has not been fully evaluated. In patients with suppurative cholangitis prompt endoscopic drainage is mandatory, since antibiotics alone will not sterilize the biliary tract in the face of obstruction. Antibiotic prophylaxis to prevent cholangitis after ERCP should be administered particularly to patients in whom biliary drainage is expected to be difficult; antimicrobial prophylaxis with piperacillin effectively prevents ERCPinduced cholangitis. Antibiotic maintenance therapy can be highly successful in the treatment of recurrent cholangitis in patients with a compromised biliary tract.