Impaired gastric emptying in gastric ulcer patients has generally been explained by gastric hypomotility. The gastric motor response to an electrical vagal stimulus was measured intraoperatively in patients with gastric ulcers (GU, n = 21), duodenal ulcers (DU, n = 25) and combined ulcers (GDU, n = 6). Amplitude and duration of the contraction and integrated motor response were found to be significantly greater in GU patients than in patients with duodenal and combined ulcers. Thus, hypermotility of the gastric muscle exists in GU patients and the delayed gastric emptying in GU disease may be the result of antropyloric motor dysfunction rather than of gastric hypotony. Abnormal motility associated with duodenogastric reflux appears to be a key feature in the pathogenesis of gastric ulcer.