Multiple sclerosis (MS) is a disease of the CNS, typically striking adults during the primary productive time of their life. The symptoms of MS can restrict the individual's physical activity and income-earning ability, resulting in a major financial burden on the patient, family, health system and society. This systematic literature review was conducted to document the economic burden of MS. Employing pre-defined search terms and inclusion/exclusion criteria, systematic searches were conducted in MEDLINE, EMBASE, PsycINFO, the Health Economic Evaluations Database (HEED), the NHS Economic Evaluation Database (EED) and the UK National Institute for Health and Clinical Excellence (NICE) website as well as conference abstracts. We identified 29 cost-of-illness studies that met the a priori inclusion criteria. The cost categories responsible for the majority of costs associated with MS varied across countries. There was a significant increase in costs associated with an increase in disease severity as measured by the Kurtzke Expanded Disability Status Scale (EDSS) score. The increase in magnitude was coupled with changes in the distribution of costs; although direct medical costs were important contributors in earlier stages of disease, they were outweighed by indirect costs in later stages, mainly due to relapses and productivity losses. Considering the increased costs associated with relapse occurrence and increasing disease severity, pharmaceutical or non-pharmaceutical interventions aimed at delaying the progression of disease may help to reduce the economic burden of MS.