Since the proposition in 1975 of the European Neogene Mammal (MN) scale by Pierre Mein, the amount of taxonomical, strati graphical and chronological information around Europe has increased exponentially. In this paper, the strati graphical schemes of three of the best studied areas for the Lower and Middle Miocene, the Aragonian type area in Spain and the Upper Freshwater Molasse from the North Alpine Foreland Basin in Switzerland and Bavaria, are compared. The correlation of their local biostratigraphies are discussed. Sixteen rodent's events are studied and ranked in the three areas according to their local biostratigraphy. This study shows, and quantifies for the first time, the significant asynchronies of the different included rodent events. The MN-system is discussed in the light of those results. In accordance, we propose that it is still useful but only in a biochronological way, as a sequence of time-ordered reference localities allowing coarse long-distance correlations. In order to obtain better temporal resolution, this system has to be combined with local biostratigraphies that are well calibrated to the time scale, implementing the information about synchrony and diachrony of mammal events in different areas. evenements. Le systeme MN est discute it la lumiere de ces resultats. En consequence, nous proposons que ce systeme reste utile seulement d 'un point de vue biochronologique, comme sequence ordonnee dans le temps de localites-reperes permettant des correlations grossieres it longue distance. Afin d' obtenir une meilleure resolution temporelle, ce systeme doit etre combine avec des biostratigraphies locales bien calibrees dans le temps, en integrant les informations de synchronie et de diachronie des evenements it mammiferes dans differentes regions.