We report five cases of carcinoma of the ampulla of Vater with another primary malignancy diagnosed either synchronously or asynchronously. These cases were observed in a group of ten Vaterian carcinoma cases diagnosed between 1988 and 1993. These cases include the first Vaterian carcinoma cases with previous breast and esophagus tumors and Ihe second case in the literature with simultaneous colonic carcinoma in the absence of familial polyposis coli and/or Gardner's syndrome. Compared with the other cancer series, the expected second primary malignancy rate in Vaterian carcinoma cases is much higher. Therefore, we suggest that, patients with an adenocarcinoma of the papilla of Vater should be investigaled for the presence of another primary malignancy.