Bacterial and viral infections have been shown to induce relapses and accelerate the progression of multiple sclerosis (MS). Vaccination to prevent communicable disease in such patients is, therefore, of key importance. Reports of potentially detrimental effects of immunization on the course of MS, however, have prompted patients and physicians to adopt a cautious attitude towards the use of vaccines. The risks associated with a number of vaccines have been investigated in patients with MS. Vaccines against some diseases, such as tetanus and hepatitis B, are not associated with an elevated risk of MS exacerbation, whereas vaccines against other diseases, such as yellow fever, are contraindicated in patients with MS. Many patients with MS receive immunosuppressive or immunomodulatory therapy, which could make them more susceptible to infectious diseases and might also affect their ability to respond to immunization. Here, we review the indications for and possible adverse effects of vaccines in patients with MS, and address issues of vaccination in the context of immunomodulatory therapy for MS.