Cerebral venous thrombosis is a clinical condition of difficult diagnosis, and poor prognosis when treatment is not started early. There is a long list of causes, and hereby we describe a case associated to prothrombin G20210 mutation. A 53-year-old man, white, was admitted with status epilepticus. After seizures control, he developed intracranial hypertension, with headache and vomiting, and bilateral papilledema. His past medical and familial history were unremarkable. He was a nonsmoker, no drug and alcohol user. CT scan and MRI showed right temporal and parietal infarct with hemorrhagic transformation. Spinal tap with opening pressure of 500 mmH2O showed normal CSF examination. MRI angiography disclosed superior sinus, right transverse and sigmoid sinus complete thrombosis. He was started with heparin and oral warfarin. In spite of anticoagulation, two months later he developed deep right inferior limb thrombosis. All the initial tests were normal, and test for prothrombin G20210 mutation was positive. He needed a much higher than conventional daily dose of warfarin to keep him asymptomatic.