RESUMEN
Despite the important achievements in clinical and experimental aspects of demylinating diseases and multiple sclerosis (MS), its pathogenesis still remains unknown. The most commonly held view is that it is an autoimmune disease, related in some way to a viral infection, that occurs in genetically susceptible hosts. Based on this, many current treatments for MS are designed to modulate the immune response and the interferons are an example. Only beta interferon has a dose dependent efficacy in phase III clinical trials, as treatment for remitting-relapsing forms. It produces a reduction in exacerbation rates and in the burden of the disease, measured by Magnetic Resonance imaging. The clinical use of beta interferon, considering the cost and large tretament period, must be cautious, reserving it only for confirmed remitting-relapsing modalities of MS. There is no clear cut evidence that beta interferon is useful for chronic-progressive MS