Leniency policies constitute an essential part of antitrust enforcement. They are crucial for the detection as well as the deterrence of anticompetitive behaviour. While the usefulness of such policies is beyond doubt, and despite a wide range of theoretical models, very few studies quantitatively investigate their efficiency. By means of regression and variance analyses, this article studies the effects of the EU’s leniency policy from 1985 until 2017. More specifically, we analyse whether the leniency notice i) influences the amount of information that companies reveal to the European Commission, and ii) impacts the duration of the Commission’s investigation. We find that leniency policy leads companies to reveal more information regarding the anticompetitive conduct. Interestingly, leniency also increases the length of investigation procedures.