Motion pictures of fluoroscopic images were obtained during the act of swallowing Ba in 15 normal subjects. Repeated projection, photographic reproduction of serial frames and "counter-offset" printing, were used to study the movements of the bolus and of soft tissues of the mouth, pharynx and esophagus. Pressures in the nose, mouth and pharynx were recorded with manometers and strain gauges. When the mandible was anchored in the occlusive position, the palate was elevated occluding the nasopharynx, the tongue moved toward the palate, forcing the bolus into the oropharynx, and then backward like a piston to force the bolus down into the pharynx and esophagus. The laryngeal orifice was partly or completely covered by re-troversion of the epiglottis, as the larynx moved upward. The bolus was propelled through the pharynx at velocities up to 28 in./sec. by the action of the tongue, supplemented apparently by the pharyngeal constrictors. Positive pressures in the pharynx were invariably recorded during deglutition. The progress of the tail of the bolus was markedly slowed as it approached the level of the clavicle. Restoration of the respiratory passages was accomplished by relaxation of the palate, descent of the larynx and, finally, by anterior displacement of the tongue.