Modified sham feeding-stimulated gastric secretion is a recognized means of testing vagal integrity. The chew-and-spit technique is esthetically distasteful and difficult to perform without some of the food being swallowed. Simple chewing of an inert substance does not stimulate acid secretion. We thus tested to determine whether chewing gum, a potent cholinergic stimulant of salivary secretion, also stimulates the stomach. We compared the gastric acid output stimulated by the chew-and-spit method, using a cheeseburger chewed for 15 min, with gastric acid output stimulated by chewing seven sticks of chewing gum over 15 min, in 12 patients with duodenal ulcer disease. Acid output stimulated by chewing gum was 36% +/- 5%, and by cheeseburger was 39% +/- 6% of pentagastrin maximum acid output (r = 0.97). We conclude that chewing gum is a simple, cheap, convenient method for testing vagally mediated gastric acid secretion.