Bariatric surgery complications are associated with the nature of the procedure, reaching an incidence of 40%. One of them is the marginal ulcer, which is defined as a peptic ulcer produced over the jejunal mucosa, distal from the gastro-jejunal anastomosis. Its reported frequency ranges from 0.6 to 25% in gastric bypass patients. Associated risk factors are bad tissue perfusion by increased tension of the anastomosis, foreign bodies as stiches or staples, acidic exposure from gastric fistula, non-steroid anti-inflammatory drugs, tobacco and infection by Helicobacter Pylori. Female patient operated with Roux en “Y” Gastric bypass for obesity, 7 months after the first surgery she required emergency surgery with laparotomy due to postsurgical complications. 3 months after this event she was diagnosed with malnutrition and almost 1 year after the initial GB she presented to the ER with abdominal pain, distension and involuntary muscle resistance. She was admitted to the ER with tachycardia, bilateral hypoventilation and abdominal pain. A CT-scan revealed hollow viscera perforation. Pouch gastrectomy and anastomosis of the gastric remnant with the Henley-Longmire jejunal loop technique for reverse bypass procedure was performed successfully. The gastric bypass reversion is essential for long term complications that do not respond to initial treatment, such as the recurrent marginal ulcers, dumping syndrome, hiatal hernias, refractory hypoglycemia’s, nesidioblastosis, and hypocalcemia.