Background: Obesity is an important risk for pathological gastroesophageal reflux. Aim: To assess the effects of gastric bypass on obese subjects with erosive esophagitis. Patients and methods: Sixty two morbid obese subjects (aged 16 to 70 years, 41 females) with erosive esophagitis at the moment of surgery were studied. These patients were subjected to a gastric bypass with gastric resection. They were followed with upper gastrointestinal endoscopy every one year, looking for the presence of erosions or ulcers in the distal esophagus. Results: The mean follow up period was 21 months. Prior to surgery all patients had heartburn or regurgitation and at two years after surgery, 97% were asymptomatic. Esophagitis was found in 97 and 6.5% before and after surgery, respectively. Two patients had an esophageal ulcer, that healed on follow up endoscopy. There was a 72% reduction of overweight on late follow up. Conclusions: Gastric bypass is effective to control pathological gastroesophageal reflux in patients with morbid obesity