This article deals with the fundamental procedural rights of companies that are targeted in the enforcement of Articles 101 and 102 Treaty on the Functioning of the European Union (TFEU) by the European Commission or the competition authorities of the EU Member States. The paper first provides a (non-exhaustive) list of such rights as applicable to the enforcement of Articles 101 and 102 TFEU by the European Commission, and explains the source of these fundamental rights in the EU legal order. The paper then examines the relationship between fundamental procedural rights and effective enforcement of Articles 101 and 102 TFEU. It argues that procedural rights often contribute to effective enforcement, but not always. The interplay between fundamental rights of legal persons and competition enforcement remains a balancing exercise, and this balancing exercise is not the same as in traditional criminal law. Finally, the paper examines the question whether or to what extent EU Member States can, for the enforcement of Articles 101 and 102 TFEU by their national competition authorities (NCAs), provide for a lower or a higher level of procedural rights than the level of fundamental procedural rights applicable to the enforcement of Articles 101 and 102 TFEU by the European Commission.