ENThe article analyses the peculiarities of the regulation of Class Action institution in the civil proceedings of Lithuania and Poland. Due to its limited scope, this article investigates the civil proceedings in the first instance courts only. The authors draw a special focus on the comparative analysis and the analysis of the effectiveness of the procedure in the current regulation by investigating both the doctrine and the available limited case law. The subject of considerations are problems relating both to the admissibility of filing a class action, as well as the course of court proceedings in cases concerning group proceedings, with particular emphasis on their differences from other procedural structures in Poland and Lithuania.