Loop duodenal switch is an end-to-side proximal duodeno-ileal bypass with a sleeve gastrectomy. The proximal duodenal stump is anastomosed to an ileal loop, 200 cm from the ileocecal valve. The procedure is a malabsorptive operation with some theoretical advantages: only one anastomosis is performed..., and so the operative time is shorter, and there is no mesenteric opening. It is not a mini-gastric bypass, as the gastric antrum, the pylorus and the first centimeters of the duodenum are preserved. The short term outcome shows a very good weight loss curve with no metabolic disturbances.