Abrupt esophageal distention occurs commonly during gastroesophageal reflux, thereby generating a circumstance favorable to esophagopharyngeal regurgitation and laryngeal aspiration of gastric refluxate. The aims of the present study were to examine the glottal response to esophageal distention by air and regional esophageal distention by a balloon. Fifteen healthy volunteers (age, 25 +/- 5 years) were studied while they were in an upright position. Using concurrent videoendoscopy and manometry, glottal and upper esophageal sphincter (UES) responses to abrupt esophageal distention by air injection (10-60 mL) and balloon distention (1.5, 2.0, and 2.5 cm) were recorded simultaneously. In addition, 6 subjects were studied with concurrent synchronized videofluoroscopy. Results showed that esophageal distention by air at a threshold volume of 10-60 mL caused vocal cord closure. The UES response to this threshold volume was variable. Volumes larger than the threshold value caused complete UES relaxation and belching. In addition to vocal cord closure, belching was accompanied by anterior movement of the glottis. On videofluoroscopy, the hyoid bone moved anteriorly in association with belching, but not with vocal cord closure without belching. Proximal esophageal distention by the balloon also provoked vocal cord closure. This response was less consistent for balloon distention in the middle and distal esophagus. It is concluded that (a) esophageal distention by either air or a balloon evokes a glottal closure mechanism, thereby suggesting the existence of an esophagoglottal reflex; (b) this reflex is elicited most easily by distention of the proximal esophagus; (c) glottal and UES responses to esophageal distention are independent from each other; and (d) the esophagoglottal closure reflex may play an important role in preventing laryngeal aspiration of acid due to gastroesophageal reflux accompanied by acid regurgitation into the pharynx.