An action to set aside an arbitral award is the only legal remedy in Poland for challenging final arbitral awards. The legal nature of the complaint has been, and continues to be, the subject of disputes in doctrine and jurisprudence, and its determination is also important for determining the practical manner in which the complaint proceedings are conducted. Following the 2015 amendments to the Code of Civil Procedure, it should be considered that this complaint constitutes an extraordinary remedy. It should be noted, however, that this extraordinary legal remedy is of a special nature due to the appropriate application to it of the provisions of the appeal procedure – the appellate procedure to a much more extended extent than is the case with other extraordinary legal remedies. More-over, it is a legal remedy aimed at setting aside an award of an arbitration court, i.e. a decision of a private body, and not a court judgment issued in the course of the administration of justice.