Endoscopic retrograde cholangiography (ERCP), the most advanced of the gastrointestinal endoscopic procedures, provides both specific diagnostic information pertaining to diseases of the biliary tract and pancreas and definitive therapy available only with this modality. ERCP is safe and accurate, establishing a primary diagnosis in 80% of cases and, in experienced hands, cannulation is successful in 98%. In addition to cholangiography, pancreatography has been a significant achievement providing accurate diagnostic yield through direct cannulation and opacification of the pancreatic duct while permitting collection of secretions for cytological evaluation and chemical analyses. The therapeutic extension of ERCP, endoscopic papillotomy (EPT), is successful in 94% of cases in the treatment of common bile duct stones and papillary stenosis, providing comparable results to surgical procedures while reducing morbidity, mortality and convalescence. Because of the accuracy and safety of these procedures, they should be considered early in suspected diseases of the biliary tract and pancreas so that the clinician can establish a specific diagnosis and provide definitive therapy.