In this study we investigated by immunocytochemistry (peroxidase-conjugated extravidin-biotin system) the existence of neuroendocrine cells in the main ducts draining the exocrine pancreas and in the ampulla of Vater of six human specimens obtained at surgery (duodenocephalopancreasectomy). Using a panel of primary antibodies for Chromogranin A, gastrin, CCK, somatostatin and serotonin (5HT), we visualized scattered neuroendocrine cells in the epithelium of Wirsung duct and in the ampulla. All were positive for Chromogranin A and the majority were also positive for serotonin (5HT), while gastrin cells were seldom observed. Interestingly, their number was far lower than in the adjacent duodenal mucosa. We believe that these neuroendocrine epithelial cells may have specific physiological roles such as epithelial trophism and differentiation.