Papilledema due to raised intracranial pressure in absence of intracranial mass arose roughly at the same time in 2 male heterozygous twins. The diagnosis of benign intracranial hypertension (BIH) was confirmed by the finding of normal cerebrospinal fluid and high opening pressure. Neurologic examination was normal. In both cases choroidal folds were evident. The relationship between BIH and genetic factors is discussed.