Laryngopharyngeal reflux (LPR) disease and extraesophageal manifestations of gastroesophageal reflux have been recognized to have dramatic effects in the upper airways. Patient-reported symptoms alone underestimate the presence of LPR, making accurate clinical diagnosis difficult. Many previous studies examine populations with only standard dual-probe pH testing that does not include a test probe in the pharynx. Therefore, documentation of acid exposure at the laryngeal inlet is lacking. In adult patients with subglottic stenosis (SGS), whether due to granulomatous disease or presumed idiopathic causes, LPR is often a contributing or causative factor. A retrospective chart review from 1991 to 1999 identified 19 patients with SGS. Ten of the 19 patients had concomitant disease states, including sarcoidosis (3), Wegener's granulomatosis (3), laryngeal trauma (3), and a history of intubation (1). Fourteen patients underwent 24-hour ambulatory pH probe testing with 3- or 4-port probes. The proximal port in either catheter was positioned by manometric guidance directly behind the laryngeal inlet. Measurements of pH of less than 4 were recorded at the level of the larynx in 12 of the 14 patients tested (86%). This finding was noted in half of the patients despite empirical therapy with proton pump inhibitors at the time of the testing. Seven of 10 patients with underlying disease were studied, and all demonstrated acid reflux in the hypopharynx. In 9 patients, the stenosis was presumed to be idiopathic. Five of the 7 patients (71%) with idiopathic SGS tested had positive pH probe studies (pH below 4 in the pharyngeal probe). Our results demonstrate a strong association of LPR and SGS. In the idiopathic group, reflux is the probable cause of their stenosis. In the group of patients with underlying disease states, reflux was involved in all tested patients and likely acts as a synergistic factor that stimulates their granulomatous disease to react and subsequently result in the development of stenosis. Evaluation for LPR with pharyngeal pH testing should be performed in all patients with SGS.