RR MS evolution has changed since the beginning of the availability of MS disease-modifying drugs (DMD). Before concluding a unique impact of the efficiency of DMD, careful analysis of long-term studies has to be conducted. Analysis of the literature points out a few bias in the long-term follow of MS patients under DMD: indication of DMD has changed since 20 years, diagnosis criteria are not the same (including the Will Rogers phenomen), and so far population are not homogeneous and comparable. Analysis criteria of the efficiency of the treatments are not the same, pending on the date of the publications. References concerning the long-term impact of DMD are in fact very limited. In addition, long-term efficiency of 2nd line treatments is not available. Another explanation of the change of MS evolution could be the lower evolutivity of MS patients since 2 decades. Analysis of placebo group in pivotal studies, argues to a decrease of the relapse annual rate and mean EDSS score in the more recent studies and recent MS diagnosed patients. To conclude, long-term evolution of MS patients is more favorable, influence of DMD is likely, but not unique.