An 18-year-old woman was admitted to our hospital because of headache and double vision. One year before, she had experienced similar symptoms which were ameliorated spontaneously. Before admission, she had been experiencing throbbing headaches for 20 days and double vision for 7 days, respectively. A brain magnetic resonance imaging (MRI) study, performed at another hospital 6 days before admission, showed no abnormality. On admission, she had paralysis of the left abducens nerve and papillaedema of the bilateral optic fundi. Magnetic resonance venography (MRV) revealed areas of signal loss expanding from the confluence of sinuses to the right transverse sinus, which confirmed the diagnosis of cerebral sinus thrombosis. Her symptoms improved dramatically with anticoagulation therapy. The present case suggests that the exploration of papillaedema of optic fundi is of paramount importance in the diagnosis of cerebral sinus thrombosis, and MRV can be definitely diagnostic despite the normal findings of conventional MRI.