Fifty-nine subjects over age 60 had a computerized tomography (CT) scan and completed four neuropsychological tests. Measurements of ventricular size and sulcal enlargement were compared to test performance. Performance of the elderly subjects was also compared to that of subjects aged 16 to 40 years. Subjects over 60 years of age had significantly more brain atrophy and more impaired test performance than younger subjects. Subjects aged 80 to 99 had more atrophy and impaired performance than those 60 to 79 years. Our results suggest that, with aging, the brain atrophies and loses its abilities as measured by neuropsychological testing. However, CT evidence of atrophy only weakly predicts impaired mental function independently of age.