A 66 year old woman was admitted for right hypochondriac pain and an abdominal tumor. A tumor of the pancreatic head with duodenal infiltration and liver metastases was found by laparotomy, and pancreaticoduodenectomy was performed. In addition, there was associated cholelithiasis and a goiter. Histopathologically, a tumor of the islets of Langerhans was suspected. The tumor tissue was positive by the Hellman-Hellerström silver impregnation method, and electron microscopy confirmed the presence of secretory granules similar to D cells. The tumor tissue contained a large quantity of somatostatin (1.3 micrograms/g). Finally, the diagnosis of somatostatin-producing tumor originating in the pancreas was made.