Background: Postoperative abdominal pain associated with pancreatitis has been reported as a pancreasassociated complication after total biliary excision. The aim of the present study was to determine pancreatic ductal patterns in the head of the pancreas and evaluate pancreatic ductal dilatation in patients presenting with postoperative abdominal pain after radical biliary excision for congenital choledochal cyst. Methods: Postoperative endoscopic retrograde pancreatography (ERP) was performed in a total of 38 patients (27 female and 11 male) with a history of postoperative abdominal pain or an increase in serum and urinary amylase on laboratory analysis. Pancreatic ductal configuration and ductal dilatation were determined. Results: Pancreatic configurations included the usual type (n = 20), ansa pancreatica type (n = 11), loop type (n = 5), and divisum type (n = 2). Dilatation of the pancreatic duct was observed in 34 patients. The common channel was dilated in 29 patients. Mild postoperative pancreatitis occurred in 4 patients in the long term. Protein plugs were observed in the dilated pancreatic duct. Conclusions: Pancreatic ductal morphological pattern and ductal dilatation, possibly caused by long-standing stagnation of the pancreatic juice, may be associated with postoperative abdominal pain and pancreatitis in congenital choledochal cyst.