The nonfunctioning islet cell tumors of pancreas are not associated with obvious sign and symptoms of hormone overproduction. Symptoms, most commonly pain and jaundice, are due to the mass effect of the tumor and invasion of the surrounding structures, and unlike functioning tumors, the location of the tumor has a direct bearing on the patient's symptoms. We have experienced a case of benign nonfunctioning islet cell tumor of the pancreas in 47-year-old female. She was admitted to our hospital due to palpable large mass of her abdomen. She had no obvious sign and symptoms of hormone overproduction. The exploratory laparatomy was done under the impression of retroperitoneal tumor with the information of radiologic finding and abdominal C-T scan. The pathologic diagnosis was benign nonfunctioning islet cell tumor of the pancreas.