The Authors report a series of seven obese women suffering from Benign Intracranial Hypertension (BIH), all submitted to radioisotopic cisternography. Cisternographic findings showed altered patterns of CSF clearance in all but one patient, suggesting that an increased arachnoid resistance to CSF efflux might be present in BIH of obese women. The pathophysiology of BIH is discussed: different pathogenetic mechanisms may contribute to its development with a relative importance depending on the specific etiology of the syndrome.