Fifteen patients experiencing a flare-up of multiple sclerosis were given 1 g methylprednosolone per day for 5 days. The EDSS score and gait analysis using spatio-temporal variables were recorded for these patients on days 0, 5 and 45. Both methods evidenced significant improvement but the significance was observed between day 0 and day 5 for the EDSS and between day 5 and 45 for gait speed and between day 0 and 45 for step rate. Gait speed was correlated with the pyramidal scale but not with the other functional scales of the EDSS. These results suggest that EDSS and spatio-temporal gait analysis are different tools for the assessment of therapeutic effect. Gait analysis can provide a precise quantitative assessment of the locomotor handicap as a function of the proposed treatment.