The neuroendocrine tumors of the pancreas are rare, but belong to the most common endocrine neoplasms of the abdomen. In most cases they present as solitary tumors, composed of monomorphic cells. Functionally active cells are associated with characteristic hormonal syndromes. Using morphological, immunohistochemical and biological criteria, the classification distinguishes between well differentiated tumors with benign or uncertain behavior, well differentiated (low grade malignant) carcinomas and poorly differentiated (high grade malignant) carcinomas. In recent years the percentage of non-functional tumors has increased.