Pseudotumor cerebri is a syndrome of increased intracranial pressure, normal cerebrospinal fluid values, and a normal cerebral ventricles on brain imaging studies. A patient with a diagnosis of pseudotumor cerebri was admitted to the authors' hospital twice within a 2.5-year interval and treated with vitamin B12 (vit-B12). At the second admission she also presented with a cerebral venous thrombosis that might have been explained by vit-B12 deficiency, homocysteinemia, and an increased level of lipoprotein-a.