Introduction: The relationship between Ηelicobacter pylori (Hp) gastritis, the most common infection worldwide and Gastroesophageal Reflux Disease (GERD), a major health problem in Western Countries, remains controversial. AIM: To investigate the association between Hp infection and GERD and the impact of Hp eradication on esophageal acid exposure and esophageal motility in Hp-positive patients with GERD. Methods: Twenty seven Hp-positive (group I) and 20 Hp-negative (group II) patients with GERD underwent endoscopy- biopsy, esophageal manometry and 24-hour pH-metry. All group I patients received eradication treatment and six months later they were re-evaluated with 24-hour pHmetry, esophageal manometry and endoscopy-biopsy. Results: There were no significant differences between the two groups regarding sex, age, grade of esophagitis, manometric and pH-metry findings. All Hp-positive patients had antrum predominant gastritis. In all group I patients’ eradication of Hp was successful. Gastritis and esophagitis were healed in all patients. The mean Lower Oesophageal Sphincter Pressure (LOSP) showed a significant increase of 11.7 mmHg before and 12.48 mmHg after eradication (p<0.04). A significant decrease in DeMeester score was observed (mean score 62.92 before versus 41.88 after eradication (p<0.01). Conclusions: 1. In patients with GERD the presence of Hp has no impact on manometric and pH-metry findings. 2 The eradication of Hp infection results in increase in LOSP with a consequent decrease in esophageal acid exposure.