Background/Aims To compare gastroesophageal reflux disease (GERD) symptoms and response to proton pump inhibitor (PPI) in patients with erosive esophagitis (EE), non-erosive reflux disease (NERD) or functional heartburn (FH) using GERD impact scale (GIS) questionnaire. Methods Total 126 patients with GERD symptoms were diagnosed as EE (n = 62), NERD (n = 34) and FH (n = 30) by endoscopy, 24-hour esophageal pH testing and Bernstein test, prospectively. Analysis of risk factors and GIS questionnaire for GERD symptoms and quality of life were performed before and 8 weeks after PPI treatment. Results EE group had a higher proportion of men, frequent alcohol consumption, smoking, hiatal hernia, body mass index ≥ 25 kg/m2 and triglyceride levels (≥ 150 mg/dL) than the other groups (all P ＜0.05). On the other hand, both psychiatric treatment and psychopharmacotherapy were more frequent in patients with FH than in those with EE and NERD (both P ＜0.05). Among GERD symptoms, chest pain was more frequent in FH group than in EE and NERD groups (P ＜0.05). Eating problems and limitation of productive daily activities occurred frequently in FH group and NERD group, respectively. GIS after 8 week PPI treatment showed improvement in all of the GERD symptoms in EE (all P ＜0.05) and in acid regurgitation, epigastric pain and hoarseness in NERD group (all P ＜0.05). In terms of quality of life, PPI treatment improved sleep disturbance in EE (P = 0.031) and limitation of productive activity in the NERD group (P = 0.001). Conclusions GIS questionnaire showed that different characteristics and symptoms improved after PPI therapy among patients with EE, NERD and FH, demonstrating the usefulness of the GIS questionnaire. (J Neurogastroenterol Motil 2013; 19:61-69).