Impaired oesophageal peristalsis may play a major pathogenetic role in gastro-oesophageal reflux disease (GORD). Therefore 55 patients with suspected GORD were studied simultaneously by ambulatory 24-hour pH and pressure monitoring with three pressure transducers (3, 8 and 13 cm above the lower oesophageal sphincter) in order to to test for a relationship between oesophageal motility and GOR. Twenty-one patients (38%) had pathological reflux; these patients had significantly more simultaneous contractions than patients without pathological GOR (30.1 +/- 3.3% vs. 19.0 +/- 1.8%, P = 0.002, mean +/- SEM). Further analysis revealed a significant difference between groups in the occurrence of simultaneous contractions in the mid-oesophagus (33.7 +/- 3.8% vs. 23.9 +/- 1.8%, P = 0.012), but not in the distal oesophagus (34.4 +/- 2.7% vs. 33.9 +/- 3.1%, P = 0.90). In addition, a moderate but highly significant correlation between the rate of simultaneous contractions and reflux time was found (r = 0.463, P = 0.0005). Mean amplitude and mean duration of the contractions were no different between groups, neither in the proximal (43.4 +/- 3.3 mmHg vs. 44.9 +/- 1.9 mmHg, P = 0.68 and 2.4 +/- 0.2s vs. 2.5 +/- 0.1s, P = 0.50, respectively) nor in the distal oesophagus (48.8 +/- 4.6 mmHg vs. 54.2 +/- 3.4 mmHg, P = 0.34 and 3.0 +/- 0.2s vs. 2.9 +/- 0.2s, P = 0.71, respectively). It was concluded that pathological GOR is associated with an increased occurrence of simultaneous contractions in the mid, but not in the distal, oesophagus.