This video presentation outlines the technical aspects of how I perform a One Anastomosis Gastric Bypass based on experience of more than 1000 cases. The importance of restoring hiatal integrity, and creation of a long, thin gastric pouch are emphasised and demonstrated as key components to minimising the risk of biliary reflux. A single layer, hand sewn gastroentostomy is demonstrated as a means of performing the anastomosis with a very low incidence of leak, haemorrhage, marginal ulceration or stenosis. The importance of the pouch emptying preferentially into the common channel rather than the BP limb is emphasised in order to avoid post prandial discomfort and nausea. Finally the case for a 150cm biliopancreatic limb in all patients (rather than the more common 200cm or longer) in order to minimise nutritional deficiencies whilst still maintaining excellent weight loss and co-morbidity resolution is presented.