Acute emphysematous cholecystitis is an uncommon form of acute cholecystitis characterized by the presence of gas within the wall, lumen of the gallbladder or biliary ducts. Recognition of this gas is of utmost importance for an adequate therapy. Based on selected case studies the significance of plain abdominal radiographs, ultrasonography, CT and radionuclide studies is discussed. Differential diagnoses and diagnostic problems are mentioned to help understand this rare, but clinically important condition.