Our aim is to present the laparoscopic technique of an emergency revisional procedure performed to convert a mini/one anastomosis gastric bypass (MGB/OAGB) to a modified Roux-en-Y-gastric-bypass (RYGB) due to recurrent bleeding from a marginal ulcer. A 43 year old woman presented unstable conditions due to acute bleeding from a marginal ulcer after a MGB/OAGB performed 3 years before. After three failed endoscopic haemostasis attempts, she underwent a laparoscopic conversion to a modified RYGB in emergency setting. The patient had an uneventful recovery. She maintained heamodynamical stability after the procedure. She was eventually discharged in the seventh postoperative day after restarting oral feeding on chronic proton pump inhibitors. To our knowledge, there are few descriptions of emergency surgical conversion from a MGB/OAGB to a modified laparoscopic RYGB due to a recurrent marginal ulcer bleeding not responsive to endoscopic treatment. A regular post-operative follow-up is mandatory after bariatric surgery. We advocate performing revisional surgery in an experienced Bariatric Center.