This paper is devoted to the impact of EU law on national leniency programmes, especially the Polish one. It analyses the jurisprudence of the Court of Justice in Pfleiderer, Donau Chemie and Schenker and identifies three specific areas of potential EU influence on national leniency programmes. The impact of EU law on the rules of access to leniency documents is analysed in detail on the basis of both EU and Polish law and taking into account the Draft Directive on Antitrust Damages Actions. The paper covers also the extent to which the principle of effectiveness of EU law limits the procedural autonomy of Member States in regard to their leniency programmes. This analysis covers both “negative conditions”, that is, elements of national leniency programmes which are incompatible with EU law, and “positive conditions”, in order words, those elements of domestic leniency programmes which are seen as necessary for securing their effectiveness.