 We plan to investigate the properties of glatiramer acetate against the recurrence of MS disease activity following high dose cyclophosphamide induced cessation detectable autoimmunity. This study is a prospective, open-label two-year follow-up study in 12 patients with relapsing-remitting MS who are unable to tolerate or have failed to optimally respond to conventional therapy and are at high risk of disease progression and loss of function. Patients who elect to enter the study will be given a single course of high-dose, cyclophosphamide regimen without transplantation. Patients will then receive 20 mg of glatiramer acetate subcutaneously 4 to 6 weeks after the last dose of high-dose cyclophosphamide, to allow the immune system to have time to begin to reconstitute without glatiramer acetate but still provide sufficient time for glatiramer acetate to vaccinate against recurrence of MS disease activity. 