Using a low-compliance pneumohydraulic infusion system, we mapped the entire esophagus of nine volunteers with no history of esophageal disease, centimeter by centimeter, to see if there was pressure symmetry throughout the esophagus during 5 mL wet swallows. We found that esophageal length varied from 21-25 cm. The esophageal low-pressure zone (LPZ) varies in distance from the upper esophageal sphincter (UES) (4-8 cm). The length of this LPZ is 2-3 cm in most subjects but low pressures (<50 mmHg) may occur for longer intervals in some. The amplitudes of most paired swallows were within 10 mmHg of each other, and in only 10% of swallows was the pressure difference more than 15 mmHg. We conclude that there is radial pressure symmetry throughout the normal esophagus. The LPZ coincides closely to the 50-50 point where the percentage of striated and smooth muscle distribution in the circular and longitudinal muscles is equal.