The Polish part of the Euroregion Silesia consists of the Association of Municipalities of the Upper Oder River. On the basis of the above-mentioned declaration about the Opole-Moravian-Silesian Euroregion signed in 1997, the former Mayor of Racibórz held the first meeting of the association founders. The meeting was attended by representatives of these municipalities: Racibórz, Kornowac, Rudnik, Baborów, Kietrz, Lyski and Lubomia. The representatives decided to file an application for registration of the Association in court and they also decided that the seat of the Association and of the Euroregion Silesia would be the town of Racibórz as for Poland. The appellation being accepted, the Association of Municipalities of the Upper Oder River was registered in Court of the Voivodeship in Katowice on 4 June 1998.

News of the foundation of the Association influenced other municipalities to join in. Głubczyce, Branice, Krzanowice, Krzyżanowice, Pietrowice Wielkie and Wodzisław Śląski whose municipal councils accepted a resolution to join the association were at the first General Meeting of the Association on 25 June 1998. Further enlargement of the Association was on 10 December 1998 (Gorzyce) and 13 May 1999 when 5 more municipalities joined the Polish members of the Euroregion Silesia (Kuźnia Raciborska, Marklowice, Mszana, Nędza and Pszów). For the next ten years of the Association's existence the amount of members has changed only twice. Currently there are 19 members in the Association.

A council and a review board were elected at the first General Meeting of the Association. Andrzej Markowiak, Mayor of Racibórz, was elected president of the council. He held the post from June 1998 to January 2007. On 29 January 2007, a new Mayor of Racibórz Mirosław Lenk was elected a new president of the Association for the first time at the General Meeting.