The velocity of the front face of a liquid saline bolus ejected from the pharynx into the esophagus was measured by recording changes of luminal electrical impedance with three sets of electrodes in 9 subjects. At a site 26 cm from the incisors, the mean velocity of the front face of the bolus increased from 10 to 70 cm sec-1 as the volume swallowed was raised from 5 to 30 ml. The velocity of the front face of the bolus was greater 26 cm from the incisors than it was 32 cm from the incisors.