Disease-modifying drugs are available in the United States for the treatment of relapsing-remitting multiple sclerosis (RRMS), including interferon (IFN) beta-1a, IFNbeta-1b, and glatiramer acetate. Another formulation of IFNbeta-1a is available in Europe, Canada, and other countries. Mitoxantrone is also indicated for the treatment of worsening forms of RRMS and secondary progressive (SP) MS. In addition to reductions in annual relapse rates and other measures of clinical disability, the disease-modifying drugs appear to reduce MRI measures of disease activity. Available data suggest that the efficacy of disease-modifying therapy is sustained for at least for 4 to 6 years. Results of clinical drug trials have been used as a rationale to support treatment of early MS with a disease-modifying drug. Other medical therapies are used in the management of RRMS, including treatments to help manage MS-related symptoms such as spasticity and bladder dysfunction, and corticosteroids to hasten recovery from acute relapses. In some situations, interventions are used to minimize side effects of disease-modifying drug therapy. Several currently marketed treatments, including IV immunoglobulin, methotrexate, and azathioprine, are being evaluated as treatments for RRMS in combination with the approved therapies. Investigational compounds, including oral formulations of glatiramer acetate and interferon, are in various stages of development.