ERCP is a difficult procedure to perform in Billroth II gastrectomy patients because of altered anatomy. We investigated the outcomes and risk factors for adverse events with ERCP using a cap-fitted forward-viewing endoscope with endoscopic papillary balloon dilation (EPBD) in Billroth II gastrectomy patients.The records for Billroth II gastrectomy patients who underwent ERCP using a cap-fitted forward-viewing endoscope with EPBD at 5 institutions between August 2008 and April 2014 were retrospectively reviewed. The outcomes and risk factors for adverse events resulting from this treatment were analyzed.In total, 165 patients were identified. ERCP was technically successful in 144 patients (87.3%) and clinically successful in 141 patients (85.5%). Adverse events occurred in 38 patients (23.0%): perforation in 3 cases (1.8%), pancreatitis in 13 cases (7.9%), and asymptomatic hyperamylasemia in 22 patients (13.3%). In univariate analysis, ≥2 ERCP sessions, periampullary diverticulum, and common bile duct (CBD) stone size ≥ 12 mm were found to be associated with ERCP-related adverse events. In multivariate analysis, ≥2 ERCP sessions (odds ratio [OR], 4.762; 95% confidence interval [CI], 1.472-15.402; P = .009) and a CBD stone size ≥ 12 mm (OR, 3.213; 95% CI, 1.140-9.057; P = .027) were significant.ERCP using a cap-fitted forward-viewing endoscope with EPBD is feasible in Billroth II gastrectomy patients. In patients with ≥2 ERCP sessions or a CBD stone size ≥ 12 mm, special attention should be paid to the possible occurrence of significant adverse events.