The various pancreatic endocrine tumors (PETs) share histological features with each other and with the carcinoid. The aspects of chemotherapy and/or interferon concern the management of metastatic disease. The value of chemotherapy is difficult to evaluate from the literature because often no distinction is made between the various types of PETs and carcinoids are often also included. Moreover, it has been shown that not each tumor responds equally to chemotherapy, depending on a functioning or non-functioning state of the tumor. In general the response rate to any cytostatic drug, single agents or combinations, is low.