We quantified vitamin A in the cerebrospinal fluid of patients with idiopathic intracranial hypertension, elevated intracranial pressure of other causes and normal intracranial pressure. Vitamin A could be detected by high-pressure liquid chromatography in most of the specimens. There was a significantly higher level of vitamin A in the cerebrospinal fluid of some patients with idiopathic intracranial hypertension. Vitamin A toxicity may play a role in the pathogenesis of idiopathic intracranial hypertension.