Background and aims: Prolonged monitoring of the flow of fluid across the pylorus in the interdigestive state has long been difficult. Our aim was to explore the use of intraluminal impedance recording for assessment of transpyloric fluid movements and to describe normal interdigestive patterns and their relationships with antroduodenal pressure waves. Subjects and methods: Twenty healthy volunteers were studied with a catheter positioned across the pylorus allowing the recording of 5 impedance signals (1 antral, 1 pyloric and 3 duodenal) simultaneously with 6 pressure signals (2 antral, 1 pyloric and 3 duodenal). Patterns induced by presence of air were verified by standard ultrasound and injection of 10 ml of air. Transpyloric Doppler ultrasound recordings made after drinking 300 ml of water were used to validate impedance patterns associated with transpyloric fluid transports. Results: Impedance patterns related with the presence of air (short-lived increases) occupied 14±12 % of the time in the antrum and 0.8±0.5 % in the duodenum, respectively (p<0.005). All fluid transport events lasting more than 4 seconds were recorded by both Doppler and impedance techniques. Transpyloric fluid transport was observed in all three phases of the antral migrating motor complex (MMC). The total number of transport events was higher in phase II (18±7) as compared with both phase I (2.6±2) and phase III (6.1±3), p<0.05. Retropropagated transport was observed mainly in antral phase I where it represented 54 % of all fluid movements, compared to 2.5 % in phase II and 18.5 % in phase III, p<0.05. In phase III, retropropagated events occurred late, when the antrum was already in phase I. During phase II, 80±13 % of the changes in impedance were observed in relation with manometric events and 72±9 % of the antral contractions were associated with transpyloric fluid transports whereas only 60±13 % of association was observed in phase III, p<0.05. The 3 duodenal phases III which lacked an antral phase III were not associated with transpyloric fluid transport. The velocity of the bolus events (3.3±2.3 cm/s) was higher than the velocity of the associated antral contractions (1.1±0.7 cm/s), p<0.05. Conclusion: Prolonged assessment of interdigestive transpyloric fluid transport events using intraluminal measurement of impedance is possible. Transpyloric fluid transport occurs during all three phases of the MMC. Manometrically detected contractions are the most frequent but not the only driving forces of these events. Retropropagated transport is normal especially in phase I and in late phase III.