Endoscopic retrograde cholangiopancreatography (ERCP) was performed less in children than in adults. Twenty-seven children, aged from 56 days to 14 years (average 6 years), received ERCP from August 1989 to December 1990. The cannulation into the papilla of Vater was successful in 24 children (88.9%) and their pancreaticobiliary ductal system was visualized clearly. Congenital biliary dilatation (CBD) was diagnosed in 16 patients and other biliary disorders in 8 patients. The APBD was confirmed in almost all CBD patients, showing a close etiological relation. It was concluded that ERCP is helpful to diagnose and differentiate pediatric biliary diseases and to study the etiology and pathophysiology of CBD.