This is a retrospective study of 100 elderly patients (36 men and 64 women aged 75 years or more) operated upon for biliary tract calculi. Thirty-one patients had one or several underlying visceral diseases and 5 had associated carcinoma of the digestive tract. Calculi of the common bile duct were present in 48 cases, and 41 patients had acute infection, including cholecystitis (14) and cholangitis (27). Surgery included cholecystectomy in every case and opening of the common bile duct in 49 cases with either choledocho-duodenal anastomosis (31 cases) or external biliary drainage (18 cases). Only one patient with gastric carcinoma died. The morbidity rate was low (11 post-operative complications) and each group of patients spent about the same time in hospital. Neither mortality nor morbidity were aggravated by the presence of calculi in the common bile duct and/or acute infection. In uncomplicated lithiasis the surgical indications mainly depend upon the severity of underlying visceral diseases. Early intervention seems desirable in most patients with acute cholecystitis or cholangitis. Surgery of the biliary tract is basically the same in elderly and in young patients, but the operation must be simple and, if possible, complete. The quality of medical surveillance and nursing has considerable influence on the results.