Multiple sclerosis is thought, by many investigators, to be an immunologic disease. Therefore, a rationale exists for treating this disease by immunosuppressive therapy. In exacerbating-remitting multiple sclerosis, corticosteroids and adrenocorticotropic hormone are the most widely used drugs; high doses of intravenously administered methylprednisolone have recently gained favor. Chronic progressive multiple sclerosis has been treated with a number of immunosuppressive regimens, several of which have shown promise to date. Cyclophosphamide and azathioprine have been used most often and are reviewed in this report, as are other agents currently under investigation. No firm guidelines for the treatment of chronic progressive multiple sclerosis can be offered, but an approach to immunosuppressive therapy is suggested in this review.