A case of persistent monocular blindness probably resulting from the post-subarachnoid hemorrhage ischemic injury of the posterior optic nerve is reported. On admission, the patient was assessed as Hunt-Hess classification grade III, Fisher group IV. Uneventful surgery for clipping the neck of her small saccular anterior communicating artery aneurysm was performed on second hospital day via left pterional approach. She complained of total blindness of her left eye as she recovered from drowsy consciousness to be lethargic on first post-operative day; her left eye showed sluggish direct pupillary light reflex and normal optic fundoscopy. Her ensuing hospital course had been complicated by symptomatic vasospasm, bleeding tendency, subacute epidural hematoma, and hydrocephalus. She was independent on discharge. Ophthalmologic evaluation on 60th post-subarachnoid hemorrhage day showed total blindness and optic disc atrophy of her left eye. Probable ischemic optic neuropathy is another cause of the post-subarachnoid hemorrhage visual disturbance, especially after the rupture of anterior communicating artery aneurysms.