Twenty patients who had taken long-term benzodiazepines were submitted to brain CT scan examinations. Some scans appeared abnormal. The mean ventricular/brain area measured by planimetry was increased over mean values in an age- and sex-matched group of control subjects but was less than that in a group of alcoholics. There was no significant relationship between CT scan appearances and the duration of benzodiazepine therapy. The clinical significance of the findings is unclear.