EN
The aim of this article is to analyse the most significant forms of trans-frontier cooperation on the Polish-Slovak common borderland since 1918. The analysis is presented chronologically, divided into stages. Polish-Czechoslovak trans-frontier cooperation is discussed in the first part of the article, including such issues as the original protected common areas, for example the Pieniny Mountains, and the convention on tourism signed in 1925. Between 1945 and 1993 the majority of the national parks in the Tatra and Sub-Tatra regions were established, and in 1956 a second Polish-Czechoslovak convention on tourism was signed. The last part of the article discusses the Trans-frontier Union of the Tatra Euroregion as a contemporarily institutionalised form of Polish-Slovak cooperation. The newest legal institution of the European Union, the European Grouping of Territorial Cooperation, is also presented. The Euroregion's final goal is to be converted into this grouping in the near future.