A case of pituitary adenoma associated is neurofibromatosis type 1 is reported. On June 6, 2000, a 49-year-old man was admitted to the Department of Neurological Surgery, Okayama University Hospital, for bitemporal hemianopsia. Twenty-nine years previously, he had been operated on for a left inguinal tumor that proved to be a neurofibroma. Based on the presence of other manifestations, such as café-au-lait spots and subcutaneous nodules, he had been diagnosed with neurofibromatosis type 1, the same as his father, sister, and daughter. Computed tomography and magnetic resonance imaging demonstrated an intrasellar mass lesion with a cystic portion in the suprasellar region. Endocrinologically, almost all of his basic hormone levels were normal. A right front-temporal craniotomy was performed for a preoperative diagnosis of craniopharyngioma, and total intracapsular tumor extirpation was achieved. The histological diagnosis was clinically silent corticotroph pituitary adenoma. Neurofibromatosis is sometimes associated with neoplasms of the central nervous system, usually optic gliomas. Associations between pituitary adenomas and NF 1 are very rare and have been reported in only four cases, including the present case.