The pressure profile of esophageal peristalsis was studied in healthy young adult males using an intraesophageal transducer assembly. The amplitude of peristaltic contractions following wet swallows was determined at intervals along the esophagus from the lower esophageal sphincter (LES) to the upper esophageal sphincter (UES). The amplitude profile revealed a trough of significantly decreased (P less than 0.05) amplitude at 17.5-20.0 cm above the LES. The change in pressure per unit time (dp/dt) produced a profile also with a significant decrease (P less than 0.01) in the upper esophagus, having good correlation (r = 0.91, P less than 0.001) with the amplitude profile. Mean velocity of the peristaltic wave in the upper esophagus varied from 2.92 +/- 0.19 (+/- SEM) to 3.29 +/- 0.36 cm/sec. In the distal esophagus, mean velocity increased significantly (P less than 0.01) to 4.98 +/- 0.38 cm/sec at 7.5 cm above the LES, and then fell significantly (P less than 0.05) to 2.15 +/- 0.27 cm/sec at 2.5 cm above the LES. This report establishes amplitude and velocity profiles in the human esophagus. The profile of the first derivative of the primary peristaltic wave (dp/dt) is also described, and its possible importance discussed.