The lower-esophageal high-pressure zones (LEHPZ) of 10 normal subjects, 8 patients with hiatus hernia and one patient with progressive systemic sclerosis (PSS) were investigated using a special 8-lumen recording catheter, and lateral orifices of which were spaced at 45 degree intervals around the circumference of the catheter. While similar pressures were recorded from all orifices within the stomach and esophageal body, pressures within the LEHPZ were found to be related to spatial orifice position. In normal subjects, but not in patients with hiatus hernia, a significnatly higher localized pressure was detected by orifices directed toward the left posterior quadrant of the circumference of the distal esophagus, while a lesser, rather uniform, pressure was recorded from the other three quadrants. From the PSS patient, who had severe gastroesophageal reflux, a LEHPZ was detected only in the left posterior quadrant. The results suggest that the recorded LEHPZ represents the summation of two factors; an intrinsic force possibly due to a physiologic lower-esophageal sphincter and an extrinsic force possibly resulting from compression of the distal esophagus by the lateral margin of the diaphragmatic hiatus.