Out of a total of 910 cholecystectomies performed on patients suffering from biliary calculosis, from January 1980 to December 1994 the Authors observed two cases of cholecysto-biliary fistulas (0.2%), a complication which can rarely affect biliary stones. In the light of the international literature and of their own, however, limited experience, the Authors take into account the pathophysiologic and clinical aspects of this pathology. They agree with the literature data on the lack of specificity of the clinical signs and uselessness of preoperative diagnostic tools, the only exception sometimes being E.R.C.P. The Authors find Csendes' cholecysto-biliary fistulas classification extremely useful as far as the subsequent surgical treatment is concerned. The latter should be electric, i.e. evaluation of each single case depending on the type of fistula, its size, conditions of its edges, dilatation of the main bile duct. Surgery may range from a simple suture of the fistula edges with endoluminal drainage, associated or not to surgery of the papilla, to a biliary digestive anastomosis.