We summarized the 3-year experience of using beta-interferon 1a (44 mcg, subcutaneously) in the form of the preparation rebif in 141 patients including 120 patients with active remitting multiple sclerosis (RMS) and 21 patients with secondary progressive MS (SPMS). All patients were examined every three months. The significant decrease in the frequency of exacerbations per year was seen already during the first year of treatment. EDSS scores remained stable in 47.37% of all RMS cases and in 57.14% of all SPMS cases during the first year. A one point and more increase of EDSS was found only in 5.26% patients during three years of treatment. The drug was well tolerated during the long period, adverse effects were found in 16.31%, with a flu-like syndrome in the first place. Only 1.42% of patients refused treatment. All other patients were highly motivated and adherent to treatment.