There is ample evidence from this retrospective comparison to indicate that emphysematous cholecystitis does merit clinical distinction apart from acute cholecystitis. It is an acute infection of the gallbladder caused by a specific group of bacteria that may be aided by some aspect of local ischemia. Cholelithiasis does not seem to be a major factor in the pathogenesis of emphysematous cholecystitis, and this, in association with some dependence upon ischemia, may account for the predominance of this disease in males rather than females. Gangrene is a common feature of the pathologic process, and thus it is not surprising that the diagnosis of emphysematous cholecystitis implies a risk of gallbladder perforation that is five times that expected from ordinary acute cholecystitis. The key to identifying this disease is the plain abdominal roentgenogram which in most instances will make the diagnosis and provide an impetus for early operative intervention.