An annular pancreas is an uncommon congenital anomaly that usually presents early in childhood. Malignancy in the setting of an annular pancreas is unusual. We herein report a case of annular pancreas with carcinoma of the papilla of Vater. A 59-year-old man presented with epigastric discomfort and was referred to us after gastroduodenal endoscopy showed a tumor of the papilla of Vater. Preoperative imaging showed the pancreatic parenchyma encircling the descending duodenum and a tumor at the papilla of Vater. A pancreaticoduodenectomy was performed for the annular pancreas and the ampullary tumor. Histological examination confirmed a complete annular pancreas and carcinoma in situ of the papilla of Vater. We also provide a review of the reported cases of an annular pancreas with periampullary neoplasms and discuss the clinical characteristics of this anomaly.