Objective: We present a rare case of bilateral blindness in a young man with sphenoid sinus mucocele.Case Summary: A male patient aged 18 years presented with three weeks history of worsening headache and vomiting. There was history of blurring of vision resulting in blindness in both eyes. He did not give any history of nasal or paranasal infection or fever. On general physical examination, there was no abnormality detected. Neurological examination revealed left ptosis, bilateral dilated pupils with afferent pupillary defect and no vision in both eyes. There was evidence of left complete ophthalmoplegia. On fundoscopy, there was bilateral papilloedema. Cranial CT scan showed a homogenously isodense well delineated lesion in the sphenoid area with lateral extensions. Also, cranial MRI revealed a non-enhancing sphenoid region lesion extending to sellar, suprasellar and parasellar areas. A diagnosis of sphenoid sinus mucocele with secondary infection was suspected. He underwent a navigation-guided transnasal sphenoidotomy. On the first post operative day, there was improvement in his visual acuity and afferent pupillary response returned on the left eye. Histology is in keeping with mucocele. He was discharged on the 8th post operative day on oral antibiotics and steroids for four weeks.Result: His visual recovery has been rather slow probably due to prolonged compression of the optic nerves and optic chiasm. Conclusion:Sphenoid sinus mucocele is one of the rare causes of blindness. Early diagnosis and prompt surgical treatment improve the outcome.