Abstract Introduction Endoscopic retrograde cholangiopancreatography (ERCP) in patients with surgically altered anatomy (SAA) is technically challenging and associated with a significant number of failures. We examined the feasibility and efficacy of a novel technique for the management of bile duct stones (BDSs), called underwater cap-assisted ERCP (u-ERCP). Methods Between June 2019 and February 2020 all patients with SAA with jaundice or cholangitis secondary to BDSs who underwent u-ERCP were enrolled. The u-ERCP technique combines the underwater advancement of a pediatric colonoscope with a transparent cap fitted on the tip of the endoscope. We evaluated the technical success, clinical success, and adverse events associated with u-ERCP. Results We describe the technique itself and our initial experience in six patients. A complete and successful procedure was carried out in all patients, with the occurrence of no adverse events. None of the patients needed additional treatments for recurrence of symptoms during the follow-up period. Conclusions u-ERCP can be considered as a promising alternative for successful endoscopic management of biliary disease in patients with SAA.