The One Anastomosis Gastric Bypass has been developed from the Mini Gastric Bypass procedure as originally described by Robert Rutledge. The modification of the original procedure consists of making a latero-lateral gastro-jejunal anastomosis instead of a termino-lateral anastomosis, as is carried out as described in the original procedure. The rationale for these changes is to try to reduce exposure of the gastric mucosa to biliopancreatic secretions because of their potentially carcinogenic effects with longer term exposure, which is the major criticism of the original technique. If we fix the jejunal loop to the gastric pouch some centimetres up to the gastro-jejunal anastomosis the biliopancreatic secretions have less possibility of coming into the gastric cavity (gravity force). Furthermore, if the anastomosis is latero-lateral this possibility is reduced even more. In addition, the intestinal loop reinforces the staple line against disruption, and also the gastric pouch against dilatation.