A large cystic tumor in the pancreatic body was found incidentally in an 85-yr-old male. A distal pancreatectomy was performed after a diagnosis of cystadenocarcinoma. Microscopic examination of the resected specimen revealed a pancreatic cystic endocrine tumor; however, this tumor produced no symptoms. Immunohistochemical studies of the tumor cells showed positivity for gastrin, neuron-specific enolase, chromogranin A, and synaptophysin, and two cell types of neurosecretory granules were recognized in electron-microscopic studies. Although endocrine tumors of the pancreas are usually solid and cystic change occurs only rarely, such tumors should be considered in the differential diagnosis of patients who have a cystic lesion in the pancreas.