Gastroesophageal sphincter pressure (GESP) and contractile waves of the esophagus were measured in 113 normal subjects ranging in age between 2 months and 74 years. The amplitude and duration of the peristaltic waves of the thoracic esophagus were similar in both children and adults. Resting GESP pressures were dependent upon age. In children under one year, high pressures were recorded. The high pressures gradually diminished until between 15 and 24 years, whereafter they remained at similar values up to 65 years. After this age, a further decline in pressure was observed. The importance of these findings are discussed.