AIM: To value whether omeprazole could induce the healing of DIS and regression of symptoms in patients with DGER. METHODS: We enrolled 15 symptomatic patients with a pathological esophageal 24-h pH-metry and bilimetry. Patients underwent endoscopy and biopsies were taken from the distal esophagus. Specimens were analyzed at histology and transmission electron microscopy (TEM). Patients were treated with omeprazole 40 mg/d for 3 mo and then endoscopy with biopsies was repeated. Patients with persistent heartburn and/or with an incomplete recovery of DIS were treated for 3 more months and endoscopy with biopsies was performed. RESULTS: Nine patients had a non-erosive reflux disease at endoscopy (NERD) while 6 had erosive esophagitis (ERD). At histology, of the 6 patients with erosive esophagitis, 5 had mild esophagitis and 1 moderate esophagitis. No patients with NERD showed histological signs of esophagitis. After 3 mo of therapy, 13/15 patients (86.7%,P<0.01) showed a complete recovery of DIS and disappearance of heartburn. Of the 2 patients treated for 3 more months, complete recovery of DIS and heartburn were achieved in one. CONCLUSION: Three or 6 mo of omeprazole therapy led to a complete regression of the ultrastructural esophageal damage in 86.7% and in 93% of patients with DGER, NERD and ERD respectively. The ultrastructural recovery of the epithelium was accompanied by regression of heartburn in all cases. METHODS: We enrolled 15 symptomatic patients with a pathological esophageal 24-h pH-metry and bilimetry. Patients underwent endoscopy and biopsies were taken from the Patients were treated with histology and transmission electron microscopy (TEM). Patients were treated with omeprazole 40 mg / d for 3 mo and then endoscopy with biopsies was repeated. Patients with persistent heartburn and / or with an incomplete recovery of DIS were treated for 3 more months and endoscopy with biopsies was performed. RESULTS: Nine patients had a non-erosive reflux disease at endoscopy (NERD) while 6 had erosive esophagitis (ERD). At histology, of the 6 patients with erosive esophagitis, 5 had Mild esophagitis and 1 moderate esophagitis. No patients with NERD showed histological signs of esophagitis. After 3 mo of therapy, 13/15 patients (86.7%, P <0.01) showed a complete recover Of the 2 patients treated for 3 more months, complete recovery of DIS and heartburn were achieved in one. CONCLUSION: Three or 6 mo of omeprazole therapy led to a complete regression of the ultrastructural esophageal damage in 86.7 % and in 93% of patients with DGER, NERD and ERD respectively. The ultrastructural recovery of the epithelium was accompanied by regression of heartburn in all cases.