Gastroesophageal pH monitoring and reflux scintigraphy were simultaneously performed in 65 children, who were being investigated for suspected gastroesophageal reflux disease. The aim of the study was to compare, peak per peak, the information provided by the two techniques during a 1-h simultaneous-recording period. During this period, 123 reflux episodes were recorded with both techniques, but only six occurred simultaneously. Significantly more reflux episodes were recorded on scintigraphy (n = 88; p less than 0.05), particularly during the first half-hour period (n = 62), if compared with the number of pH drops greater than 1 unit, even at pH levels higher than 4 (n = 41; p less than 0.05). It is concluded that the two techniques explore differently the reflux phenomenon.