Classification JEL : L43, L51, L92National audienceThis paper discusses the interest to introduce yardstick competition to improve regional rail regulation. After reminding informational benefits and theoretical limits of yardstick competition, the main practical applications of comparison mechanisms are presented. The applicability analysis of yardstick competition to French regional railways reveals a great opportunity for a practical application. Moreover, the econometric estimation of a cost frontier shows large efficiency differences between the regions, corresponding to more than 100 M€. Last, a practical application of comparison mechanism is proposed to give SNCF incentives to reduce those efficiency differences.Cet article analyse ...