Despite major advances in surgical and nonsurgical therapy, biliary tract infections remain a significant cause of morbidity and mortality. The two classic biliary tract infections most commonly encountered are acute cholecystitis (either calculous or acalculous) and acute cholangitis. In addition, bile leakage associated with bile duct injuries during laparoscopic cholecystectomy has become a problem not infrequently encountered by surgeons. Acute calculous cholecystitis results from a combination of mechanical, biochemical, and infectious mechanisms, initiated by stone impaction in the cystic duct. After instituting empiric antibiotics, early laparoscopic cholecystectomy should be performed. Although conversion to open cholecystectomy is more common than in chronic cholecystitis, there appears to be no increased morbidity or mortality in that setting. Acute acalculous cholecystitis usually occurs in critically ill patients and may present both a diagnostic and therapeutic dilemma. Aggressive management, however, is warranted, both because of the critical nature of illness in these patients and the high incidence of perforation. Percutaneous cholecystostomy is indicated, particularly in high-risk patients both for diagnosis and treatment. Acute cholangitis results from a combination of bactibilia and biliary obstruction. The majority of patients can be successfully managed with intravenous antibiotics and fluid resuscitation. In those patients in whom initial management is not successful, biliary drainage, which is best accomplished nonoperatively, should be instituted. There is a very limited role for early surgical intervention in acute suppurative cholangitis. Biliary leaks resulting in bile "peritonitis" or bilomas are common sequelae of laparoscopic bile duct injury. Although surgeons may feel it is necessary to operate urgently, delineation of the proximal biliary anatomy via percutaneous transhepatic cholangiography and biliary stent placement is the appropriate first step in management. This procedure will usually control the bile leak and allow delineation of the anatomy and opportune timing of definitive reconstruction.