Objectives/Hypothesis: Deterioration of aerodigestive tract reflexes such as the esophagoglottal and pharyngoglottal closure reflexes and pharyngeal swallow has been documented in the elderly. However, the effect of aging on the contractile response of the upper esophageal sphincter (UES) to pharyngeal water stimulation has not been studied. The aim of this study was to characterize the pharyngo-UES reflex in the healthy elderly. Methods: We studied nine healthy elderly (7761 y[SD]; four men, five women) and nine healthy young volunteers (2662 y[SD]; four men, five women). AUES sleeve sensor was used to measure the pressure. We tested pharyngeal stimulation induced by rapid pulse and slow continuous injection of water. Results: The volume of water required to stimulate the pharyngo-UES contractile reflex by rapid pulse injection in the elderly (0.56 34 0.1mL) was significantly higher than that in the young (0.16 0.02mL) (P<0.05). In contrast to young subjects, there was no pressure increase in resting UES pressure observed in the elderly for continuous pharyngeal water infusion. In both young and elderly, the threshold volume for the pharyngo-UES contractile reflex was significantly lower than that for pharyngeal swallows. Conclusions: The pharyngo-UES contractile reflex deteriorates with aging. This deterioration is primarily due to abnormalities of the afferent limb of the reflex. Key Words: Upper esophageal sphincter, airway protection, pharyngeal stimulation.