Homocystinuria presenting as cerebral venous thrombosis is not usual. We report on a 13-year-old boy who was admitted to the hospital due to severe headache, nausea, vomiting and fever (38 degrees C). The patient was Marfan like and presented left hemiparesis and meningeal irritation sings. He was mentally retarded, had severe myopia, and had right lens dislocation one month before. Cranial CT scan was suggestive of cerebral venous infarct. MRI and magnetic resonance angiography showed venous infarcts more prominent in the right thalamic projection with hemorrhagic transformation and multiple foci of cortical (occipital and parietal bilaterally) deep parietal and left capsular bleeding, secondary of thrombosis of the transverse and sigmoid venous sinuses. High levels of homocysteine were detected in the blood and urine. Homocystinuria is an autosomal recessive inborn error of methionine metabolism caused by cystathionine-beta-synthase defect in most cases. We discuss the clinical and radiological findings in this patient, analyzing the pathophysiology of the thrombotic events related to homocystinuria.