ABSTRACT
Insulinoma is rare functioning islet cell tumor of pancreas and its main feature is frequent attacks of hypoglycemia. Because of frequent seizure, the disease is occasionally mistook as epilepy. We experienced a case of insulinoma with dilantin toxicity in a 45 year old patient who had been treated with dilantin for 7 years. Selective splenic arteriogram showed 0.8cm mass in the tail of pancreas which was proven insulin secreting tumor on histiopathological examination. After operation no more seizure attack was detected and her blood sugar level was well maintained within normal range. This case might provide an insight that the possibility of insulinoma should be considered in patient with episodic neurobehavioral dysfunction such as epilepsy.