Reflux after One Anastomosis Gastric Bypass (OAGB) may be Acid, Non-Acid, or mixed. This presentation defines the incidence of reflux after OAGB, and describes the investigative approach, including the roles of upper endoscopy, impedance pH, biliary scintigraphy and reflux isotope studies. It then outlines the key treatment modalities, including hiatal repair, fundoplication using the remnant stomach, Braun anastomosis, and conversion to Roux-Y, as well as their effectiveness.