Summary: In this study, pH metry was simultaneously applied with a new technique, the intraluminal multiple electrical impedance (IMP) procedure, for measuring gastrointestinal motility for gastroesophageal reflux (GER) detection. Seventeen infants with clinical symptoms of GER disease such as recurrent apnea, aspiration pneumonia, wheezing, and failure to thrive were investigated during two feeding periods. A single catheter combining a pH electrode with seven electrodes for impedance measurements over a distance of 8.5 cm was used for the investigation. In all patients, 185 acid episodes were detected by pH metry. In 106 of these 185 acid episodes, a unique pattern in the IMP readings was noted, indicated by a retrograde esophageal volume flow. These episodes were regarded as acid GER episodes. Seventy-one of the 185 acid episodes occurred during the clearance process of a preceding acid GER characterized by typical IMP readings of an anterograde bolus transport. Eight of 185 acid episodes were missed in the IMP readings for technical reasons. The IMP pattern described as characteristic for a GER was observed in 490 other episodes not detected by pH metry. More than 75% of all GER detected by IMP reached the pharyngeal space; 73% of all GER occurred during feeding and the first 2 postprandial hours and 27% occurred during the remaining time until the next feeding. Even during the latter period, 34% of GER were detected by IMP only; they were missed by pH metry. Volume clearance indicated by IMP was always completed earlier than acidity clearance. The results show that IMP technique facilitates the detection of all GER, whereas pH metry is confined to the measurement of acid GER. Therefore, this technique might improve the evaluation of GER disease and detection of GER in conditions with gastric hypoacidity.