Twenty-five patients studied by serial metrizamide (Amipaque) CT cisternography were used to analyze CSF kinetics. Delayed CSF flow patterns were noted in 7 patients, while intermediate patterns occurred in 4. The abnormal cisternogram was characterized primarily by ventricular reflux and stasis and secondarily by diminution of the parasagittal blush and a periventricular rim of decreased absorption. The intermediate group had minimal ventricular stasis after 24 hours and a normal parasagittal blush. After clinical and biochemical evaluation of the patient with dementia, CT scanning is usually indicated. If a profile suggestive of communicating hydrocephalus emerges, CSF kinetics can be monitored dynamically by CT scanning with metrizamide enhancement.