This paper concerns 433 patients who were operated on for cholelithiasis in my department during the 14 years between 1947 and 1960.Incidence of GallstonesThe stones in question have been classified as "gallbladder stones" and "common-duct stones" on the basis of anatomic location (Table 1). In the first group are those stones found only in the gallbladder. In the second group are gallstones found not only in the gallbladder but also in the common bile duct, as well as stones found in the common bile duct alone. The incidence of gallstones in both groups was found to be about equal. The distribution of stones on the basis of sex also was about equal but was slightly higher in female patients who had gallbladder stones. The distribution of gallstones on the basis of patients in several decades also is included in Table 1. The maximal incidence of gallbladder stones was