On the grounds of the analysis of 1300 case records and own observations with the use of angioscopy and angiography the authors have come to the conclusion that acute cholecystitis in elderly individuals results from the blood supply disorder in the gallbladder wall, caused by the thrombosis of the vascular branches of the cystic artery. They have suggested the classification of acute cholecystitis, mirroring the stage character of the disease and the nature of pathological changes in the gallbladder.