A control group of 53 patients with selective vagotomy plus pyloroplasty was studied with pre- and postoperative cholecystography. At the fourth to seventh years the size and motility of the gallbladders were the same. Gallstones developed in two patients. A series of 91 patients with total vagotomy plus pyloroplasty was studied by similar methods. In 46 patients the gallbladders were grossly dilated and in 30 of the 46 the gallbladders were noncontractile. Gallstones developed in nine of the 46 patients. In the other 45 patients hypotonic dysfunction of the gallbladder was insignificant, and stones developed in only 1 of them. Explanation of these variable results is thwarted by unknown variations in the degree of both hypotonic dysfunction of the gallbladder and lithogenic change in the bile of patients with complete hepatic and complete celiac vagotomy after total vagotomy, and also by the unknown occurrence of incomplete hepatic and incomplete celiac vagotomy in series of allegedly complete total vagotomy. It is concluded that total vagotomy increases the incidence of gallstones, and that this increase occurs primarily in patients with significant hypotonia of the gallbladder. Selective vagotomy prevents these sequelae.