The sphenoid sinus is the least common site of mucocele of all paranasal sinuses. It is very rare in children, especially in those younger than 12 years when pneumatization of the sphenoid sinus is completed. We report a case of histologically proven sphenoidal mucocele in a 5-year-old child. The child presented with an acute onset of significant visual impairment and headache. His vision gradually improved after trans-nasal sphenoidotomy and drainage of the sinus content with return of complete normal baseline vision after 2 months.