Abstract: Objective To investigate the association between esophageal motility and acid reflux in patients with gastroesophageal reflux disease (GERD). Methods A total of 94 patients with typical reflux symptoms such as heartburn, regurgitation and chest pain, whose score (Sc) of reflux diagnostic questionnaire (RDQ) was greater than or equa1 to 12 were enrolled in the study. Each participant was evaluated by upper gastrointestinal endoscopy, high resolution manometry (HRM) of esophagus and 24 h esophageal pH monitoring. The participants were divided into groups of reflux esophagitis (RE) and non-erosive reflux disease (NERD) on the basis of endoscopy findings. The 24 h esophageal pH monitoring categorized participants into physiologic reflux (pH ^-) and pathologic reflux (pH ⁺). The aracteristics of esophageal motility and acid reflux were compared between the two groups of participants. Results Lower but non-significant differences (P>0.05) were found in pressure of lower esophageal sphincter (LESP), length of lower esophageal sphincter (LESL), esophageal contraction amplitude (CA), distal contractile integral (DCI) and effective peristalsis proportion (EPP) in the participants in the RE group compared with those in the NERD group. Participants in the RE group had significantly higher prevalence of reduced LESP (63.0% vs. 31.7%, P<0.01) and hiatus hernia (HH) (37.0% vs. 14.3%, P<0.05) than those in the NERD group. pH ⁺ was more prevalent in the RE group than in the NERD group (63.0% vs. 17.5%, P<0.01). Indicators of 24 h esophageal pH monitoring were significantly higher in participants in the RE group compared with those in the NERD group (P<0.05). Participants with pH ⁺ had significantly lower LESP, CA and higher HH and prevalence of reduced LESP compared with those with pH ^- (P<0.05). LESL, DCI and EPP were lower in those with pH ⁺ compared with those with pH ^-, but without statistical significance (P>0.05). Conclusion RE is closely associated with acid reflux and hiatus hernia. Esophageal dysmotility is more likely to appear in patients with pH ⁺. The interaction of acid reflux and esophageal dysmotility may play a role in GERD.