(Polish title: 'To dobra granica, ale przydalby sie jeszcze lewy brzeg Odry'. Wokól dyskusji na temat polskiej granicy zachodniej w drugiej polowie lat 40. XX w.). The author focused on the hot discussion in the Polish press and among the researchers and politicians that concerned the shape of the Polish Western frontier. According to the decisions of the victorious powers during the conference in Potsdam, in the summer 1945, Poland obtained the German Eastern territory up till the line of the lower reaches of the Oder (Odra) river (together with Szczecin) and Lausitzer Neisse (Nysa Luzycka) in order to administer it by the final solution at the peace conference. Making the frontier line based on a natural watercourse was only apparently simple. Delimitation of the waters of two states can be based on the mathematical pointing of the middle of the river (what changes a little gradually) or on the midstream (what also changes its course). These problems and a common in Poland opinion that Polish-German relations would be still bad, caused that some people proposed a new frontier line based on the German bank of the river. The proposals were connected with the conviction of the Polish elites of that time that beaten Germany would become strong again and threaten Poland, even if not militarily, at least by making inland navigation difficult. It would endanger Polish access to the sea in the Szczecin-Swinoujscie area. At last the frontier from 1945 was not corrected, nevertheless events in 1950s and 1980s showed that even GDR, ideological ally of then Poland, threatened Polish integrity in the area joined in 1945.