To determine whether cholecystectomy might be a factor predisposing to gastric ulceration, we evaluated the frequency of prior cholecystectomy in the 181 residents of Rochester, Minnesota, who had gastric ulcer diagnosed at the Mayo Clinic during the 10-year-period from 1966 to 1975. This frequency was similar to that in a control population from the same city, matched for age, sex, and time of registration at the Mayo Clinic. This was also true for subgroups of benign gastric ulcer. However, the frequency of prior cholecystectomy was higher in patients with type 1 ulcer than in those with type 2 or 3 ulcer, probably as a result of the relative predominance of older women in the type 1 ulcer group. These data do not support the hypothesis that cholecystectomy may be harmful in predisposing to gastric ulceration.