Recent studies suggest that vagal nerve dysfunction may be important in the aetiology of gastro-oesophageal reflux disease. Delayed oesophageal transit and slowed gastric emptying occur frequently and may also be of pathogenic importance. In 48 patients with gastro-oesophageal reflux disease we studied the prevalence of and relations between autonomic nerve dysfunction (as assessed by cardiovascular reflex tests) and oesophageal transit, oesophageal motility, gastric emptying, and endoscopic grade of oesophagitis. Of the 48 patients, 21 (44%) had abnormal autonomic nerve function, which was predominantly parasympathetic. Oesophageal transit was delayed in 28% of the patients and gastric emptying of the solid component of the meal was delayed in 46%. Oesophageal transit was significantly (p less than 0.007) slower in patients with abnormal autonomic nerve function. The percentage of synchronous oesophageal contractions was related to the score for autonomic nerve dysfunction (r = 0.40, p less than 0.05). There was no significant relation of autonomic nerve dysfunction to either delayed gastric emptying or endoscopic grade of oesophagitis. We conclude that in gastro-oesophageal reflux disease there is a high prevalence of parasympathetic nerve dysfunction which relates to delayed oesophageal transit and abnormal peristalsis and may therefore be of pathogenic importance.