Interferon-beta-1b was the first drug found to slow the progression of relapsing-remitting multiple sclerosis, with a reported decrease in the relapse rate of up to 34%. The present study involved 35 patients treated with interferon-beta-1b for one year. The aims of the study were: a) to compare the changes in the relapse rate and the number of days of hospitalization with other data, b) to compare the steroid needs required to treat relapses for one year before and in the year of interferon-beta-1b treatment. Our data indicated that the relapse rate may decrease as much as 77% following the introduction of interferon-beta-1b treatment. The adverse effects and the changes in the EDSS grades were similar to the published data. The duration of hospitalization decreased by 84% and the amount of methylprednisolone needed for remission by 78%. This data suggest that the impairment of the condition of the patients may be delayed considerably, while some of them can continue to work for a longer period, the standard of life of these patients therefore being more tolerable.