THE POSSIBILITY of gangrenous cholecystitis developing in a patient must be entertained whenever there is delay for any reason in the surgical treatment of acute cholecystitis. To consider this advanced, and sometimes catastrophic, inflammatory disease of the gallbladder, all patients seen at Henry Ford Hospital, with gangrene of the gallbladder, were studied critically. By definition we plan to discuss patients in whom there is complete necrosis of some portion, or most of the gallbladder wall. From 1918 to 1965, the diagnosis of chronic cholecystitis was made in 17,041 patients. During this period a diagnosis of acute cholecystitis was made in 2,236 patients. In 45 patients of this latter group, the diagnosis of gangrenous cholecystitis was made either at operation or postmortem examination. The proportion of chronic cholecystitis to acute cholecystitis to gangrenous cholecystitis in this study is approximately 379:50:1. Analysis of Cases The incidence of gangrenous cholecystitis according to age