A 39 year-old female patient suffering from amenorrhea over the course of the last 14 years was admitted to our hospital on Dec. 12, '89. Computed Tomography revealed a relatively high-density mass extending over the suprasellar portion and the sphenoid sinus. Enlargement and destruction of the sella turcica was demonstrated clearly by the plain craniogram ++. Right carotid angiography demonstrated an open siphon and a medially pointing aneurysm on the right anterior siphon. Two staged operations were performed. On Jan. 23, '90, a transsphenoidal operation was performed to remove the part of the tumor invading the sphenoid sinus. Two weeks later, on Feb. 9, '90, a transcranial operation was carried out for extirpation of the residual adenoma and direct neck clipping of the aneurysm. The tumor was subtotally removed through a left fronto-lateral craniotomy. By drilling away the tuberculum sellae and the planum sphenoidal the aneurysm was completely clipped via a contralateral approach. The postoperative neuroradiological examinations demonstrated that the aneurysm was clipped successfully and the adenoma was extirpated almost totally.