Electron scanning microscopy was applied to investigate the surfaces within the human brain ventricular system in order to establish their age-related changes. The brains were studied in different age groups and in patients with senile dementia. The changes of ependymal surfaces were manifested in the loss of ependymal cell's cilia and microvilli. These changes were marked in dementia patients. Two types of age-related changes were detected in aqueductal surface ependymal cells but its lumen was never narrowed.