Background: Intravenous methylprednisolone (IVMP) has been shown to hasten recovery from attacks of multiple sclerosis (MS) without altering the long term evolution of the condition; however, there is little evidence available to suggest which patients are more likely to benefit from IVMP treatment. Objective: To measure clinical change after IVMP treatment and to identify predictors of good outcome. Methods: Retrospective open-label study of medical records from 51 patients with clinically isolated syndromes or relapsing-remitting MS treated with IVMP for an acute attack (54 attacks). Results: A measurable neurological improvement was observed at one month in 44% of these attacks; the only predictor of Expanded Disability Status Scale (EDSS) change at one month was the severity of the attack. Conclusion: Attack severity predicts good response to IVMP when measured by means of EDSS.