Treatments for multiple sclerosis (MS) are only partially effective and most require a parenteral route of administration and/or may have severe side effects. Dimethyl fumarate is the active compound of BG-12 recently licensed for the treatment of relapsing-remitting MS. The pivotal Phase III trials have demonstrated an approximately 50% reduction of relapse rates compared with placebo paralleled by a reduction in new lesion formation on MRI. A dose of 240 mg two-times a day had an optimal effect. Flushing and gastrointestinal symptoms (diarrhea, abdominal pain, nausea) were common adverse events in the first month(s) of treatment. Severe side effects were not more common than in the placebo group for a treatment period of 2 years. The mode of action is not exactly clear and both immunomodulatory effects and an activation of the transcription factor Nrf2 are suggested. This new oral drug will be a welcome addition to existing MS treatments.