A 53-year-old female with a functioning pituitary adenoma was found to also have an unruptured asymptomatic aneurysm in the cavernous sinus portion of the internal carotid artery on MRI. The adenoma had a suprasellar extension with optic chiasm compression and extended into the right cavernous sinus. An aneurysm-like flow-void adjacent to the left internal carotid artery in the sella and embedded in the adenoma was also found. The aneurysm was confirmed by conventional angiography. We used a right fronto-pterional approach to clip the aneurysm and to remove the pituitary tumor in a one-stage procedure. The outcome was good on long-term follow-up. It is important to thoroughly evaluate the anatomic relations around the sella turcica prior to procedures with limited exposure, including transsphenoidal surgery, to avoid unrecognized complications and morbidity.