Roux-en-Y gastric bypass is the most common performed bariatric surgery. A small gastric pouch is created, leaving a narrow gastrojejunal anastomosis, with a long jejunal limb. Very little is known regarding the behavior of this pouch years after surgery. To determine through prospective sequential endoscopic studies the size of the gastric pouch, the diameter of the anastomosis, and the behavior of H. pylori infection after surgery. In 130 patients subjected to resectional gastric bypass, several routine sequential endoscopic (until 120 months) and histological evaluations of the gastric pouch were performed. After surgery, a mean of 3.6 endoscopies/patient were performed. Macroscopically nearly 95% of the small gastric pouches were normal, and the main pathological finding was a marginal ulcer. Erosive esophagitis disappeared in 93% of the patients. There was no increase in the orocaudal size of the pouch during this period of observation. There was no dilatation of the diameter of gastrojejunal anastomosis. Near 54% of all patients had normal fundic mucosa, while 18% had chronic active gastritis, coincident with H. pylori infection. Five patients had intestinal metaplasia. Based on this sequential endoscopic evaluation, there was no increase in the orocaudal size of the gastric pouch nor increase in the diameter of the gastrojejunal anastomosis. H. pylori behavior was inconsistent and difficult to interpret.