Proximal gastric vagotomy is an operation consisting of division of all vagal fibers to the acid-secreting portion of the stomach. These fibers are usually divided along the lesser curvature of the stomach; however, because of a high rate of duodenal ulcer recurrence in some series, it has become apparent that it is important to divide the vagal fibers to the stomach leaving the main vagal trunks along the distal 5 cm of esophagus in order to achieve both adequate control of acid secretion and also a lower duodenal ulcer recurrence rate. The data presented in this study of ten mongrel dogs suggest that, in the dog, division of the vagal fibers along the lesser curvature is more important in reducing acid secretion than is esophageal vagotomy; but the data also emphasize the contribution of the vagal fibers along the distal esophagus since a marked reduction in 2 DG-stimulated acid secretion can only be achieved by dividing the vagal fibers around the distal esophagus as well as those along the lesser curvature.