In adults, esophageal motor responses facilitate forward, or aboral, transit during swallowing, and protect the aerodigestive tract during retrograde movement of the bolus, which may occur with gastroesophageal reflux. It is unclear in the pediatric literature whether the activation of appropriate esophageal motor defense responses occurs during these events in infants. This investigation therefore studied the esophageal motor responses during the basal state and upon esophageal stimulation in infants. Using the water-perfusion manometry technique and a specially designed manometric catheter, 3 likely mechanisms that may protect the aerodigestive tract were recognized: secondary peristalsis, esophago-upper esophageal sphincter contractile reflex, and esophagodeglutition response.