our purpose is to report a case of cranial venous thrombosis causing pseudotumor syndrome, where the principal clinical manifestation was severe bilateral vision loss. a 24-year-old man presented with severe bilateral vision loss, transient obscuration of vision, headache, bilateral papilledema and constricted visual fields. computed tomography as well as neurologic examination was unrevealing. a lumbar puncture disclosed an increased cerebrospinal fluid opening pressure and complete blood count (cbc) showed increased numbers of platelets. a brain magnetic resonance imaging disclosed characteristic sings of chronic papilledema and suggestive signs of superior sagital sinus thrombosis. a cranial magnetic resonance venography disclosed thrombosis of superior sagital, transvers and sigmoid sinuses. the patient was treated with an optic nerve sheath decompression in the left eye, acetazolamide and anticoagulation. his ocular evaluation showed reduction of the papilledema, but severe vision loss remained. pseudotumor cerebri with severe vision loss can be the presenting sign of cranial venous thrombosis secondary to a potentially life-threatening hematologic disorder.