We report the case of a 40-Year-old woman with duodenal gangliocytic paraganglioma of the ampulla of Vater. Preoperative diagnosis was periampullar tumor. Final diagnosis of duodenal gangliocytic paragangioma of the ampulla of Vater with negative margins was made by histological and immunohistochemical study of surgical ampullectomy specimen. This case report stresses the yield of immunohostochemical study in the diagnosis of duodenal gangliocytic paraganglioma, a rare entity.