Approximately 340 therapy-naïve MS patients with relapsing-remitting form of the disease will be randomized to receive Avonex alone or Avonex plus methylprednisolone (MP). Patients will receive MP as 500 mg po for 3 days every month or matching placebo. The patients are followed on a 3-monthly basis for 4 years with disability as the primary parameter of efficacy over that time.