Cholangitis is an infection of the biliary ductal system that results from the combination of bactibilia and biliary obstruction. Choledocholithiasis has been the leading cause of cholangitis. However, in recent years, especially at tertiary referral centers, nonoperative biliary manipulations, often in patients with unresectable malignancies, have become the most common cause of cholangitis. As a result, the complete triad of fever and chills, jaundice, and abdominal pain, as originally described by Charcot, is now seen less frequently. Most patients still have leukocytosis and abnormal liver function tests, but many patients with indwelling tubes may develop cholangitis without significant jaundice. E. coli, Klebsiella species, and the enterococci remain the most frequently isolated organisms, and anaerobes including Bacteroides fragilis are recovered in 15% to 30% of patients. However, Enterobacter and Pseudomonas species, as well as yeasts, are now being isolated more frequently from patients with indwelling tubes, who often have been treated previously with antibiotics. Computed cholangiography usually is necessary to determine the cause and site of biliary obstruction. In the majority of patients with cholangitis, cholangiography can be delayed until the patient has been afebrile for a minimum of 24 to 48 hours. Initial therapy includes bowel rest, intravenous fluids, and antibiotics. Many antibiotic regimens are now available to cover the gram-negative aerobes, the enterococcus, and the anaerobes that are likely to be causing the biliary infection. The combination of a penicillin and an aminoglycoside has been the gold standard. However, recent studies suggest that the newer broad-spectrum penicillins provide adequate therapy for these patients. Only a small percentage (5%-10%) of patients with toxic cholangitis require emergency biliary decompression. The choice of percutaneous or endoscopic drainage should be made on the basis of the presumed site and cause of obstruction as well as local expertise. The nature of the biliary obstruction may be the most important determinant of outcome. At present, patients with end-stage malignant obstruction account for most of the deaths, whereas approximately 95% of patients survive an episode of cholangitis.