The case of a 60-year-old man with a 6-month history of cerebrospinal fluid (CSF) rhinorrhea is presented. Computed tomography (CT) and magnetic resonance (MR) imaging revealed an intrasphenoidal mass extending through a bony defect of the roof of the left sphenoid sinus. Transnasal surgical repair was performed; intraoperatively the mass was identified as an intrasphenoidal encephalocele. The pathogenesis of this anomaly is analyzed, the clinical findings and the operative treatment are described, and the literature is reviewed.