Patient: Male, 48 Final Diagnosis: Gallstone ileus in biliointestinal bypass Symptoms: Abdominal pain • jaundice • vomiting Medication: — Clinical Procedure: — Specialty: Surgery Objective: Unusual clinical course Background: Biliointestinal bypass is a malabsorptive procedure for surgical treatment of morbid obesity. It is the evolution of jejunoileal bypass, and it is characterized by a cholecysto-jejunostomy on the proximal end of the excluded jejunum, therefore, allowing bile flow through the excluded bowel loop reducing the risk of postoperative diarrhea and malabsorption syndrome. Obesity is a well-known risk factor for cholelithiasis; moreover, bariatric surgery has been showed to increases the risk of gallstones formation. Case Report: A 48-years-old male (body mass index 42 kg/m2) received a laparoscopic biliointestinal bypass. Nine years later, the patient received a cholecystotomy for removal of biliary stones. No surgical procedures were performed on the cholecysto-jejunostomy. Fourteen years after the bariatric treatment, the patient underwent enterolithotomy after a diagnosis of gallstone ileus. The impacted biliary stone was documented in the excluded loop proximal to the anti-reflux valvular system. The postoperative course and 1-year follow-up were uneventful. Conclusions: Few cases of gallstone ileus following biliointestinal bypass have been described in the literature. We report a new case and also propose few tips and tricks for cholelithiasis and gallstone ileus prevention after biliointestinal bypass.