This article is a review of 20 clinical trials of various forms of elective surgical treatment of chronic duodenal ulcer conducted between 1964 and 1975, some of them prospective and others retrospective in nature. Comparisons have been made of the results following truncal vagotomy with drainage, truncal vagotomy with antrectomy, and partial gastrectomy. Additionally, selective vagotomy and truncal vagotomy have been compared in some studies and various forms of drainage, such as pyloroplasty and gastrojejunostomy, have been compared in others. In general, the results of all current forms of elective surgery for chronic duodenal ulcer have been very good, and the differences among the effects of the various procedures have been small. There have been no significant differences in the mortality rates associated with the several operations when they have been performed electively. The rate of ulcer recurrence and incidence of diarrhea have been somewhat higher after truncal vagotomy with drainage, whereas the frequency of dumping and amount of weight loss have been somewhat greater after all forms of gastric resection. Selective vagotomy appears to be associated with less frequent and severe diarrhea than does truncal vagotomy. There have been no apparent differences in the results of the various drainage procedure that have been combined with vagotomy. Highly selective vagotomy without drainage, the most recent operation for duodenal ulcer, has resulted in the lowest incidence of post-operative side effects of any surgical procedure in current use. However, the frequency of ulcer recurrence after this therapeutic measure remains to be determined by long-term studies.