Multiple sclerosis (MS) is a life-long disease that typically affects young adults. The introduction of disease-modifying therapy has changed the clinical and social burden of the disease. Safety, tolerability and efficacy profiles of Interferon beta (IFNbeta) therapy in MS have been widely highlighted both in trial settings and in daily clinical practice. However, there is a relative lack of information on the long-term period: all pivotal trials must be considered short-term in a disease with an average duration of 30-40 years and post-marketing studies suffer from some limitations. Moreover, current available IFNbeta preparations are only partially effective and are difficult to administer, which has led to poor patient compliance. Over the treatment period, a problem could be the development of neutralising antibodies (NAbs) against the drug, which have been related to lessening treatment benefits. Despite these restrictions, IFNbeta still remains the first choice treatment in MS.