Acute acalculous cholecystitis, like calculous cholecystitis, generally shows diffuse inflammation throughout the gallbladder and cystic duct obstruction. Nonvisualization of the gallbladder on hepatobiliary scanning is typical [1 , 2]. We report an unusual case of acute acalculous cholecystitis in which acute inflammation was focal but severe enough to result in perforation. Hepatobiliary scanning showed both a patent cystic duct (i.e., gallbladder filling) and free intraperitoneal spill of radionuclide.