OBJECTIVES: To perform prolonged ambulatory recordings of antroduodenal motor activity in humans. METHODS: Antroduodenal manometric recordings were performed in 20 normal subjects (12 male, eight female, ages 19-41 years), using a 5-channel solid state catheter assembly (three antral, two duodenal transducers) positioned under fluoroscopy. A glass electrode simultaneously recorded pH in the antrum. RESULTS: Continuous, simultaneous recordings of antral and duodenal motor activity were obtained for 22.5 +/- 0.3 h. During fasting, 131 complete migrating motor complexes (MMCs) were recorded (6.6 +/- 0.9/subject). The average interval from onset of recording to completion of the first MMC cycle was 498 +/- 19.24 minutes. Significant diurnal variations were observed in MMC frequency (awake vs asleep: 0.25/subject/h vs 0.64/subject/h; p < 0.05), period (shorter during sleep), phase I duration (longer during sleep), and phase II duration (shorter during sleep). Among females, MMCs were more frequent and shorter. After meal administration, duodenal recording sites demonstrated a typical "fed" response; antral distension and/or retrograde catheter movement, on meal ingestion, however, precluded reliable antral "fed" recordings. CONCLUSIONS: Prolonged ambulatory antroduodenal manometry provides detailed and reliable information on fasting antral and duodenal motor activity, antral distension, and/or retrograde catheter migration on meal ingestion; there are limits, however, to the usefulness of this methodology for the evaluation of the fed motor response in the antrum.