After testing the validity of the concept of city systems in the Russian context, we assessed interest of several urban models in apprehending Russian cities and comparing them with other city systems. Gibrat's model, for instance, showed an interesting ability to describe the mechanisms of urban growth. Deviations from this model were sought by studying the specific trajectories of different city groups, on various time scales (from one and a half centuries to a couple of decades). These deviations reveal factors of different types - political, economic, localisation of resources and historical accidents.