Cognitive impairment is common in multiple sclerosis and although deterioration has been observed in individual patients at the time of relapse, improvement in cognitive function in parallel with remission of neurological impairment has proved more difficult to document. We describe a 21-year-old women with a one-year history of relapsing remitting multiple sclerosis, who was admitted to hospital following a severe relapse which rendered her quadriplegic. Detailed psychometric assessment was carried out during relapse and on recovery of neurological function, eight weeks later. There were improvements in arithmetic, naming, and comprehension tasks. The patient had T2 weighted and gadolinium-enhanced magnetic resonance imaging and magnetic resonance spectroscopy. These showed a reduction in lesion size, lesion enhancement, and changes in brain chemistry which parallel the improvement in cognitive performance.