Abstract Directive (EU) 2019/1 of the European Parliament and of the Council of 11 December 2018, to empower the competition authorities of the Member States to be more effective enforcers and to ensure the proper functioning of the internal market, obliges Member States to harmonize the law governing, amongst others, the powers of national competition authorities, including investigative powers. The Act aimed at the transposition of this directive was passed in Poland with a significant delay. This article analyses the provisions of the Act of 16 February 2007 on competition and consumer protection, in force on 4 February 2021 (the deadline for the transposition of Directive 2019/1), regulating the investigative powers of the president of the Office of Competition and Consumer Protection (UOKiK), and the changes in the relevant scope adopted by the Act of 9 March 2023 amending the Act on competition and consumer protection and some other acts. The research problem includes determining whether the regulations that were in force between 4 February 2021 and 20 May 2023 governing the investigative powers of the UOKiK president, in connection with proceedings for infringement of the prohibition of competition-restricting practices, were in line with the requirements of Directive 2019/1 and whether the abovementioned amendment act removed any existing discrepancies.