The pathophysiological mechanisms of damage to the gastric mucosa of Ethanol and alcoholic beverages are poorly understood. There are scant retrospective epidemiological studies that determine if a relationship between alcohol consumption and PUD exists. Although alcohol is not associated with an increased risk of PUD, patients with PUD are advised to avoid alcoholic drinks. Basic science studies have showed that instillation of pure ethanol at lower concentrations (4-40% v/v) causes hemorrhagic gastritis in a dose-dependant fashion. Also a synergistic relationship exists between ethanol and NSAID´s, since both cause mucosal injury. On the other hand, there are no studies available about the effect of alcohol on marginal ulcer development after RYGB.