Endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard for the treatment of patients with pancreaticobiliary disorders, but endoscopic therapy is very difficult to carry out in patients with a Roux-en-Y anastomosis. We herein present the results of ERCP for patients with a Roux-en-Y anastomosis using a double-balloon endoscope. Six patients (six men with a mean age of 69 years) who had undergone prior gastric resection with Roux-en-Y reconstruction were enrolled in the present study and underwent ERCP and associated procedures. ERCP was carried out with a double balloon endoscope, which has one balloon attached to the tip of the endoscope and another attached to the distal end of the soft overtube. In all patients, entering the Y loop was successfully accomplished, and the papilla of Vater was also reached in all cases (100%). Cannulation was successful in four patients (66.7%). The final diagnosis was choledocholithiasis in two patients, biliary fistula in one patient and pancreatic cancer in one patient. A needle-knife precut papillotomy was carried out after placement of a bile duct stent in two patients, and injection of N-butyl-2-cyanoacrylate into a biliary fistula was carried out in one patient. None of the patients suffered from any complications. A double balloon endoscope is therefore considered to be useful for carrying out ERCP and associated procedures in patients with a Roux-en-Y anastomosis.