Abdominal CT has in many cases become the initial radiographic examination to elucidate the cause of obscure abdominal pain, fever of unknown origin, and other difficult diagnostic abdominal problems. Not infrequently, unsuspected disease involving the gallbladder may be encountered. Computed tomography commonly identifies calcified gallstones, occasionally indicates acute cholecystitis, and clearly determines the extent of gallbladder carcinoma. Other less common entities such as gallbladder perforation, porcelain gallbladder, and milk of calcium bile may be diagnosed if suspicion is high and attention directed to anatomic details of the gallbladder and adjacent organs. A review of abdominal CT performed during a 4.5 year period revealed 20 instances of unusual gallbladder diseases in 16 patients. Most often these were encountered incidentally or during CT evaluation of nonspecific abdominal problems.