Nineteen moderately impaired patients with clinically definite multiple sclerosis and an initially relapsing-remitting course were included in a neuropsychological and magnetic resonance imaging (MRI) follow-up study. The average test/re-test interval was about 2 years. The neuropsychological findings were indicative of a very mild overall impairment; the patients, as a group, showed no evidence of cognitive deterioration in the follow-up period. A numerical estimation of the severity of cerebral demyelination shown by MRI did not indicate a significant change. No correlation between cognitive performance variations and MRI changes was found.