Objective To investigate the prevalence of non-acidic reflux in patients with gastroesophageal reflux disease and its correlation extent with heartburn symptom by 24-hour combined multichannel intraluminal impedance-pH (MII-pH) monitoring. Methods Consecutive patients with chief complain of heartburn in gastrointestinal specialty clinic were enrolled. Patients were divided into erosive esophagitis (EE) group, non-erosive reflux disease (NERD) group after upper gastrointestinal endoscope, further diagnosed with 24-hour combined MII-pH monitoring and rabeprazole test. The MII-pH parameters were compared in these two groups. Results 36 cases of EE and 62 of NERD were enrolled. There was significant difference in acidic reflux frequency and acidic reflux time percentage between these two groups (P=0. 001 and 0. 002). The frequency of non-acidic reflux in EE and NERD groups was 37.3% (663/1777) and 44.3% (1220/2754) respectively (x2 =21. 723,P = 0. 000). The percentage of heartburn symptom positive index in patients with acidic reflux, non-acidic reflux , and total reflux in EE group was 36.1 % (13/36), 19.4 % (7/36) and 55.6%(20/36) respectively, while in NERD group was 27. 4% (17/62), 6.4 % (4/62) and 33.8% (21/62).Conclusion The percentage of non-acidic reflux in EE and NERD groups was 37.3% and 44.3%respectively, and the non-acidic reflux was highly related to heartburn symptom. Key words: Gastroesophageal reflux disease; Erosive esophagitis; Non-erosive reflux disease; Esophageal combined multichannel intraluminal impedance monitoring