Abstract. Gastric bypass is considered by many to be the gold standard for surgical treatment of obesity. Gastric bypass was a natural evolution from gastric operations that were used for the treatment of peptic ulcer disease. Gastric bypass, first described in 1967, has undergone many modifications. It presently exists as a hybrid operation. Gastric bypass operation has been extensively scrutinized and evaluated against other operations for the treatment of obesity. Co-morbidities due to severe obesity are usually ameliorated or arrested after the weight loss from gastric bypass. Gastric bypass operation is now being performed with a perioperative morbidity of less than 10%. The average percentage excess weight loss with gastric bypass is 70%. The success rate, defined as 50% excess weight loss after at least 2 years of follow-up, is 85%. The metabolic deficiencies of gastric bypass are controllable with supplemental intake. This report with special references to the Fobi pouch operation, a modification of gastric bypass done by the author, presents the evolution, modifications, risks, outcome, and future trends of gastric bypass for treatment of obesity.