Mucocele of the sphenoid sinus is rare. Only about 130 case reports have appeared in the English literature since it was first described by Berg in 1889. The sphenoid sinus lies deep within the skull at the crossroads of 13 sensitive structures, so sphenoid sinus mucocele may be accompanied by a variety of signs and symptoms, which confuse the diagnosis and may lead to its mismanagement. Correctly managed, this condition should completely resolve; however, there is a mortality associated with delay or misdiagnosis. We have recently experienced one case of sphenoid sinus mucocele which presented with complete loss of vision. The mucocele was removed by sphenoethmoidectomy via the midfacial degloving approach.