We investigated the effects of gum chewing on pharyngeal and esophageal pH levels in patients with laryngopharyngeal reflux (LPR) who were undergoing reflux testing. Forty consecutive, unselected, adult patients who were undergoing ambulatory double-probe (simultaneous pharyngeal and esophageal) pH monitoring for diagnosis of LPR were asked to chew 2 sticks of gum 4 times during their pH studies. Twenty subjects chewed regular sugarless gum, and 20 subjects chewed a sugarless gum containing bicarbonate. The subjects recorded the beginning and end of each gum-chewing period. The mean pH values for the gum-chewing intervals and for comparable pre-gum-chewing intervals were analyzed statistically for both the pharyngeal and esophageal probe data. The regular gum group and the bicarbonate gum group were analyzed separately. In addition, the gum-chewing pH data were compared to controls, ie, normal postcibal buffering effects. The data show that gum chewing consistently increases esophageal and pharyngeal pH, and that bicarbonate gum causes greater increases than regular gum. For patients with LPR, gum chewing appears to be a useful adjunctive antireflux therapy.