Pituitary adenoma coexisting with cerebrospinal fluid(CSF) rhinorrhea and carotid aneurysm is extremely rare. CSF rhinorrhea may cause pneumocephalus and intracranial infection. Rupture of the aneurysm may cause fatal consequence. The authors report such a rare case to draw more attentions. A 55-year-old man presented with sexual dysfunction for 2 years. The serum prolactin was tested as 1,600 ng/ml(normal range, 1.39–24.2). Enhanced cranial MR showed an evident lesion at the sellar area, invading the right cavernous sinus. Prolactinoma was diagnosed. He took bromocriptine for one year and received gamma knife therapy thereafter. Four months after the treatment of gamma knife, he got CSF rhinorrhea and nasal bleeding. The endoscopic transnasalsphenoidal approach was performed to resect the tumor and repair the dura defect.The CSF rhinorrhea stopped after the surgery, however his nasal bleeding continued. The digital subtraction angiography(DSA) showed an aneurysm at the right cavernous internal carotid. The endovascular coil embolization was performed to treat the aneurysm. The patient recovered well. The coexistence of CSF rhinorrhea and pituitary adenoma is a high risk factor for the rupture of cavernous internal carotid aneurysm. When treating patients with pituitary adenoma and CSF rhinorrhea, doctors should exclude the aneurysm. When nasal bleeding occurs, the hemorrhage of internal carotid should be considered, and appropriate measures should be taken immediately.