Tumors of Vater's ampulla are generally uncommon. In this location intestinal type adenomas are frequently found, followed by noninvasive papillary neoplasms of the pancreaticobiliary type and neuroendocrine tumors (carcinoids). Carcinomas of Vater's ampulla represent about 0.5% of all gastrointestinal malignancies. Intestinal type adenocarcinoma is the most common malignant epithelial tumor followed by the pancreaticobiliary type adenocarcinoma. Highly malignant neuroendocrine carcinomas of Vater's ampulla are very uncommon. Carcinomas of the ampullary region can be sporadic or a component of several disease syndromes. Designation of large carcinomas as tumors with an ampullary or extra-ampullary origin can be difficult but is of relevance for a TNM conform classification. Helpful in the decision are the relationship between the tumor centre and Vater's ampulla, the existence of premalignant lesions in the ampullary epithelium as well as histology and immunostaining of the tumor.