AIM: To determine the prevalence and characteristics of bile reflux in gastroesophageal reflux disease (GERD) patients with persistent symptoms who are nonresponsive to medical therapy.METHODS: Sixty-five patients (40 male, 25 female;mean age, 50 ± 7.8 years) who continued to report symptoms after 8 wk of high-dose proton pump inhibitor (PPI) therapy, as well as 18 patients with Barrett's esophagus, were studied. All patients filled out symptom questionnaires and underwent endoscopy,manometry and combined pH-metry and bilimetry.RESULTS: There were 4 groups of patients: 22 (26.5%)without esophagitis, 24 (28.9%) grade A-B esophagitis,19 (22.8%) grade C-D and 18 (21.6%) Barrett's esophagus. Heartburn was present in 71 patients (85.5%) and regurgitation in 55 (66.2%), with 44 (53%)reporting simultaneous heartburn and regurgitation. The prevalence of pathologic acid reflux in the groups without esophagitis and with grades A-B and C-D esophagitis was 45.4%, 66.6% and 73.6%, respectively. The prevalence of pathologic bilirubin exposure in these 3 groups was 53.3%, 75% and 78.9%, respectively. The overall prevalence of bile reflux in non-responsive patients was 68.7%. Pathologic acid and bile reflux was observed in 22.7% and 58.1% of non-esophagitic patients and esophagitic patients, respectively.CONCLUSION: The high percentage of patients poorly responsive to PPI therapy may result from poor control of duodenogastroesophageal reflux. Many patients without esophagitis have simultaneous acid and bile reflux, which increases with increasing esophagitis grade.