Radionuclide hepatobiliary imaging is a useful procedure for the diagnosis of acute cholecystitis. Visualization of the gallbladder essentially rules out acute cholecystitis. Nonvisualization suggests acute cholecystitis but may also be associated with chronic gallbladder disease or other conditions. We recently observed five patients in whom a rim of increased parenchymal liver activity was seen adjacent to the gallbladder fossa. All five patients had acute gangrenous cholecystitis. The rim of increased activity appears to be a useful secondary sign of acute cholecystitis.