Twenty-one patients with primary empty sella were studied with computed tomography iopamidol cisternography. Ten milliliters of iopamidol at a concentration of 200 mg I/mL was administered intrathecally via the lumbar route. Eleven patients had a partial and 10 a complete empty sella. In six cases the third ventricle had prolapsed to the level of the interclinoid plane. There was no relationship between the clinical presentation and the grade of empty sella. The quality of the images obtained was always good or excellent. Cisternographies were performed in all of the patients although in 13 of them the correct diagnosis could have been achieved with a standard contrast-medium-enhanced computed tomography scan. The overall complication rate was 29%. Four patients (19%) had mild headaches and nausea; two patients (10%) had more severe side effects: vomiting, discomfort, and meningism. Computed tomographic cisternography with low-concentration iopamidol is a safe diagnostic procedure that allows a definite visualization of the anatomic alterations that occur in patients with empty sella. We think that this procedure should always be employed in symptomatic patients.