Objective To study the prevalence and characteristics of gastroesophageal reflux disease (GERD) in patients with idiopathic pulmonary fibrosis(IPF).Methods A total of 48 patients with diffuse parenchymal lung disease(DPLD) including 25 IPF and 23 other DPLD were enrolled from Department of Respiratory Disease in the First Affiliated Hospital of China Medical University.All patients were subjected to 24-hour esophageal pH monitoring.Pulmonary function test and HRCT of lung were performed at the same time.Results The prevalence of GERD in IPF patients was 64.0％,which was significantly higher than that in other DPLD patients.DeMeester scores were significantly higher in IPF patients than those in non-IPF group[(22.8 ± 21.5) score vs (15.7 ± 14.0) score respectively P ＜ 0.05].Numbers of reflux longer than 5 minutes [(3.8 ± 4.1) time vs (2.1 ± 2.1) time respectively) and reflux index (1.8 ± 1.7 vs 1.3 ± 1.2) in IPF group were higher than those in non-IPF group,yet without statistical significance.Patients with IPF had significantly higher values of following parameters than those in non-IPF patients including percentage of total reflux time(pH ＜ 4.0) (9.2 ± 5.1) ％,percentage of upright reflux time (8.5 ± 5.2) ％,percentage of supine reflux time (10.8 ± 10.7) ％,numbers of reflux (54.2 ± 22.7) time,numbers of regurgitation longer than 5 minutes (6.3 ± 4.2) time,thelongest reflux time (14.5 ± 15.3) min,reflux index 2.5 ± 1.7 and DeMeester scores (34.9 ± 20.3) time (P ＜ 0.05).DeMeester score was positively correlated with gastroesophageal reflux diseases questionnaire (GerdQ) score (r =0.667,P ＜ 0.01).The prevalence of typical GERD sympotoms in the IPF-GERD patients was higher (heartburn 7/16,regurgitation 6/16) than that in IPF patients without GERD (heartburn 2/9,regurgitation 1/9).Conclusion Patients with IPF have a high prevalence of GERD,but usually without typical GERD symptoms.In the hospitals 24-hour esophageal pH monitoring not available,GerdQ can be used to identify GERD in IPF patients.