A purpose of the article is the analysis of legal solutions concerning opposition proceedings on a trade mark application adopted by the legislator in the Industrial Property Law and their comparison to the Union procedure for opposition. The provisions of both substantive and procedural law on opposition proceedings in trade mark law in relation to several recent amendments of the Industrial Property Law have been assessed herein. The following aspects of legal solutions contained in the Polish Law and the Union procedure for opposition have been compared herein: entities who have standing to file a notice of opposition, grounds and time limits to file a notice of opposition, examination of admissibility of the opposition, a course of opposition proceedings, and the procedure for the examination of the opposition that has been deemed unfounded by the applicant. Furthermore, the article has voiced some criticism against certain solutions adopted by the Polish legislator which refer, among others, to incomplete regulation of opposition proceedings in trade mark law, a narrowed group of entities empowered to file a notice of opposition, a need to make the content of an opposition more precise, and unjustified abolition of the examination of an opposition in the course of adversarial proceedings. The considerations made herein resulted in the formulation of conclusions de lege ferenda.