Multiple sclerosis (MS) is an autoimmune disease of the central nerv-ous system characterized by inflammatory demyelination and some axonal damage. An overactive or dysfunctional immune response to self-antigen is believed to be the pathogenic mechanism and therefore the treatment of MS often involves immunosuppressive therapy. Be-cause of altered immune function in patients with MS, questions arise about risk of infections in this population and the safety and efficacy of common immunizations. The risk of MS exacerbation with common infections and safety and efficacy of immunization are reviewed along with the available guidelines for use of vaccines in patients with MS.