Fundoplication is the most widely used antireflux method, whereas Roux-en-Y duodenal diversion (partial gastrectomy, vagotomy, and Roux-en-Y reconstruction) has been used in fewer patients with more complicated gastroesophageal reflux disease. Abnormal esophageal pH values are normalized after successful fundoplication. However, very little is known about possible changes in the pH profile after successful Roux-en-Y duodenal diversion. A total of 37 patients with severe gastroesophageal reflux disease were treated by fundoplication (n=22) or Roux-en-Y duodenal diversion (n=15). Postoperatively all patients in both groups were symptom free and healing of esophagitis was verified endoscopically. After fundoplication, the 24-hour esophageal acid exposure decreased significantly (P=0.03) and the pH profile normalized (pH<4 in 5.8%+/-2.4% of the recorded time). However, the decrease in esophageal acid exposure was not significant (P=0.77) after successful Roux-en-Y reconstruction and the pH profile remained abnormal (pH<4 in 15.1%+/-4.3%). It was concluded that 24-hour esophageal pH monitoring is a reliable means of assessing the results of fundoplication, but the current test criteria should be reexamined in evaluating the results of Roux-en-Y duodenal diversion. Healing of esophagitis after Roux-en-Y duodenal diversion despite abnormal acid reflux, as shown by 24-hour pH measurements, suggests that duodenal contents also have a role in the pathogenesis of esophagitis in an acid milieu.