It is important to prevent pancreatic leakage and maintain pancreatic duct patency after pancreaticoduodenectomy (PD). We used an implantation method and a pancreatic stent in pancreaticogastrostomy (PG) and achieved good results without pancreatic leakage; however, PG strictures were observed in some cases. Using a pancreatic stent, we evaluated the early postoperative changes in the remnant pancreatic duct diameter in patients with a mildly dilated pancreatic duct.We retrospectively analyzed 46 patients with a mildly dilated pancreatic duct (diameter 4-7mm) who underwent PD with PG. They were divided into 2 groups on the basis of the surgical treatment they received for pancreatic stump: Group C included patients who underwent complete ligation of the pancreatic duct with a pancreatic stent (complete external drainage of the pancreatic juice), and Group I included patients who underwent pancreatic duct-to-mucosa anastomosis with a pancreatic stent (incomplete external drainage of the pancreatic juice).The postoperative mean diameter of the remnant pancreatic duct was significantly smaller in Group I (6.22±0.81mm) than in Group C (6.80±1.10mm) (p<0.0466).To prevent pancreatic leakage and maintain pancreatic duct patency, duct-to-mucosa anastomosis with a pancreatic stent is useful for patients with a dilated pancreatic duct.