Multiple sclerosis is an inflammatory disease of the central nervous system associated with demyelination and axonal damage. It is the leading cause of acquired non traumatic disability in young adults. Current treatments include immunomodulators (interferon beta glatiramer acetate), immunosuppressants (mitoxantrone) and natalizumab, a monoclonal antibody that prevents activated lymphocyte transmigration in the central nervous system. Many candidate drugs are being evaluated in relapsing-remitting forms. Their efficacy is encouraging but is offset by toxicity, including severe infections. None of these new treatments has proven effective in the progressive phase of the disease, in which axonal damage is prominent and partly independent of the inflammatory component.