As it is evident from the title, in my thesis I would like to provide an overview of the undertakings' procedural rights in proceedings under Article 101 and/or 102 of the Treaty on the Functioning of the European Union. Given the extensive investigative powers that are granted to the European Commission by the Council Regulation No 1/2003 and the consequences of being found guilty of violating Article 101 and/or 102 of the TFEU, it is necessary to ensure that the undertakings have enough ways available to exercise their right to defence and other rights and privileges guaranteed by the EU law and international treaties such as European Convention on Human Rights (e.g. the right to respect for private life). For this reason the EU law provides a range of procedural rights that should guarantee that both all the fundamental rights are observed and also serve as a system of checks and balances that prevents the misuse of the Commission's investigative powers. My thesis will focus individual rights of undertakings that are provided to them by the Council Regulation No 1/2003 and EU courts judicature. I will analyse their scope and purpose, the conditions under which they can be exercised and their limitations. Simultaneously a comparison between the rights of undertakings in the EU and U.S. legal system will...