The authors studied 333 acute cholecystitis out of 2,200 operated on for lithiasis of the gall-bladder, 186 bacteriological tests were carried out on the vesicular liquid and wall. They insist on the main anatomo-pathological characteristic: early, partial or total destruction of the mucous together with acute inflammatory lesions of the wall and even sometimes necrosis. This irreversible lesion is due to the acute obstruction of the gall-bladder by blockage of a calculus. Acute cholecystitis are practically always aseptic at the beginning. Sepsis is a secondary complication. These anatomo-pathological and bacteriological elements have two therapeutic corollaries: 1. The patient has to be operated very early at the aseptic stage. 2. Preliminary antibiotherapy becomes useless. Under these conditions there is practically no death before the age of 65. Mortality concern old people, operated late and suffering from other disease.