A 41-year-old woman diagnosed with RRMS since the age of 29. Given the lack of effectiveness of interferon-beta, it was decided to switch to natalizumab (EDSS 2), without the appearance of new outbreaks during this treatment. This drug was discontinued after two years due to positive VJC serology and, after a four-month washout period (PL) without any pharmacological treatment, it was decided to start fingolimod (EDSS 2). Two months after onset and after radiological stability of the disease for more than two years, three new demyelinating lesions appeared on brain magnetic resonance imaging (CMR) with no clinical evidence of a flare-up. Thereafter, the disease was radiologically stable until 28 months later, when the patient suffered a flare-up with an increase in the number of lesions in both semioval centres. Despite the clinical worsening after the resolution of the flare (EDSS 3), the patient continues on fingolimod (30 months from onset to date). Regarding the safety of fingolimod, lymphopenia was evident from baseline (300-900 cells/mmc), not leading to withdrawal.