Pneumobilia, or air within the biliary tree of the liver, suggests an abnormal communication between the biliary tract and the intestines, or infection by gas-forming bacteria. Pneumobilia usually can be distinguished from air in the portal venous system by its appearance on computed tomography (CT) scan. The most common conditions associated with pneumobilia include: 1) a biliary-enteric surgical anastamosis, 2) an incompetent sphincter of Oddi, or 3) a spontaneous biliary-enteric fistula. Three cases of pneumobilia associated with its most common causes are presented and further differential diagnostic possibilities as well as the implications of this finding on patient management are discussed.