Nonobstructive dysphagia is a common symptom of gastroesophageal reflux disease, and may be present in up to 45% of patients. To elucidate the mechanism of dysphagia, stationary and ambulatory motility studies were performed in 10 controls and 27 patients with gastroesophageal reflux disease. Sixteen patients had nonobstructive dysphagia and 11 had no dysphagia. During stationary studies, there was essentially no difference in esophageal body motility among all the groups. Lower esophageal sphincter manometry was similar in patients with or without dysphagia. On ambulatory motility, about 40% of contractions in the body of the esophagus were simultaneous in the supine position in controls and both groups of patients. The rate of simultaneous contractions decreased in the upright position and at mealtimes in controls and in patients without dysphagia, but not in those with dysphagia. This resulted in a higher percentage (38%) of intraprandial simultaneous wave activity in patients with dysphagia than in those without dysphagia (23%) or in controls (13%) (p less than 0.05). Patients with reflux disease who suffer from nonobstructive dysphagia therefore have a motility disorder measurable on ambulatory motility studies which results in an increased percentage of nonperistaltic (simultaneous wave) activity during mealtimes.