The economic transparency of football clubs has become one of the most demanded aspects as a consequence of the approval of the Transparency Law in Spain. The aim of this work is to determine whether transparency, together with other economic and sporting variables, influences the efficiency of Spanish first and second division football clubs. In the first stage, efficiency is estimated using DEA bootstrapping. In the second stage, by means of a truncated regression, the weight of transparency on efficiency is studied. In 2015, transparency has a positive influence on the efficiency of football clubs, but not in 2019.