AP-HP Hopital Europeen Georges Pompidou 1 article published in JoVE Medicine One-anastomosis Gastric Bypass (OAGB) in Rats Matthieu A. Siebert1, Jean-Marc Chevallier2, Diego D'Aurelle de Paladines1, Yohann Pottier1, Simon Msika1,3, Maude Le Gall1, André Bado1, Lara Ribeiro-Parenti1,3 1Institut national de la santé et de la recherche médicale (Inserm) unité mixte de recherche (UMR) 1149, Unité de formation et de recherche (UFR) de Médecine Paris Diderot, Universit é Paris Diderot, Assistance Publique-Hôpitaux de Paris (AP-HP), 2Department of digestive Surgery, AP-HP Hôpital Européen Georges Pompidou, 3Department of General and Visceral Surgery, Bichat-Claude Bernard University Hospital This protocol is for the performance of one-anastomosis gastric bypass (OAGB) on rat. The operator performs a long and tubular-stapled gastric pouch followed by hand-sewn anastomosis. For this model, the operator reproduces the same ratio between biliopancreatic and common limb in humans; therefore, the biliopancreatic limb measures 35 cm.