Changes in the cerebral white matter in relation to aging were studied quantitatively by computed cranial tomography (CT) in 70 healthy subjects aged 30 to 94 years. There were no age-related changes in the CT number of the white matter (WMCT) in 41 younger subjects aged 30 to 65 years. But, there was a significant negative correlation between age and the WMCT in 29 elderly subjects aged 66 to 94 years. Brain atrophy was significantly correlated with the WMCT. The WMCT decreased with aging even in neurologically healthy elderly persons.