A 30-year-old woman was referred to us because of hypoglycemic attack. The tumor on the pancreatic body of 22 mm size was revealed by close inspection, and was diagnosed as insulinoma. Surgical resection was performed, but curative resection was impossible because the component of adenocarcinoma infiltrating into surrounding tissue coexisted with insulinoma. Postoperatively, we make a diagnosis of combined tumor of the pancreas, i.e. mixed duct-islet cell carcinoma. In this paper, we discuss this rare disorder and summarize 33 cases reported in the Japanese literature.