Esophageal dysmotility is frequently associated with gastroesophageal reflux disease (GERD). The aim of this study was to investigate the relationship between the severity of reflux esophagitis and esophageal dysmotility and evaluate the effect of prolonged treatment with proton pump inhibitor (lansoprazole 30 mg/day) on esophageal motility in patients with severe reflux esophagitis associated with esophageal motility disorder. Twelve healthy subjects (HS) and 100 patients with reflux disease were involved in the study consisting of two parts: (i) comparison of esophageal motility in HS and patients with non-eroseive reflux disease (NERD), mild esophagitis and severe esophagitis; (ii) effect of 3-6 months lansoprazole therapy on esophageal motility in 23 patients with severe esophagitis, pathologic acid reflux and esophageal peristaltic dysfunction. Results included the following. (i) Esophageal dysmotility was noted in both patients with NERD and erosive GERD. (ii) Severe esophagitis was associated with severe esophageal dysmotility. (iii) Healing of severe esophagitis did not improve esophageal dysmotility. The resting lower esophageal sphincter pressure was 3.9 mmHg (range 1.7-20) before treatment and 4.8 mmHg (range 1.2-18.3) after esophagitis healing (P = 0.23, vs. before treatment), the amplitude of distal esophageal contraction was 28.8 mmHg (range 10.9-80.6) before treatment and 33.3 mmHg (range 10.0-72.5) after esophagitis healing (P = 0.59, vs. before treatment) and the frequency of failed peristalsis was 70% (range 0-100%) before treatment and 70% (range 0-100%) after esophagitis healing (P = 0.78, vs. before treatment). Both esophageal motility disorders and acid reflux play important roles in the mechanism of GERD, especially in severe esophagitis. Esophageal dysmotility is not secondary to acid reflux and esophagitis; it should be a primary motility disorder.