The article explores the discursive questions connected with the preparation and conclusion of the Ukrainian-Polish treaty of Hadiach in 1658. In particular, the content of the agreement and factors that led to the fact that the idea of the Hadiach treaty (realignment of the Commonwealth into a state of three nationalities) remained unrealised are analysed. The attention was paid to the fact that Polish-Ukrainian negotiations and the conclusion of the agreement in the set near Hadiach in 1658 were conditioned by a number of factors relating to the current Ukrainian-Polish, Ukrainian-Moscow and Polish-Moscow relations. The prime factor that made the Hetman’s government of Ivan Vyhovsky negotiate with the authorities of the Polish-Lithuanian Commonwealth was the fact that it looked for a medium of reconciliation and further state development of Ukraine because there was a growing threat from Moscow. In Warsaw, in return, having made the most from the dire situation of Ukraine, the authorities longed for solving the “Ukrainian question” by the peaceful return of the lost Ukrainian territories in 1648. They also hoped that in the context of successful development of negotiations with Chigirin, it would be possible to get an advantage over Moscow in the long-running confrontation over dominance in CEE. The content of the treaty of Hadiach that was worked out during the long negotiations mirrored the trend when the Ukrainian part, which was more interested and acted with a weak diplomatic hand, had to agree to the terms dictated by Warsaw. Although, in general, the position of Ukraine in the reformed Polish-Lithuanian Commonwealth should have resembled the position of Lithuania, Chigirin was forced to accept territorial restrictions, Warsaw's refusal to liquidate the church union, and so on. The author concluded that the prime factor, which eventually led to the collapse of the idea of Hadiach, was the reluctance of the Polish political elite to recognise equal rights for Ukraine and the Cossacks, and the fact that Warsaw sleepwalked when Moscow troops invaded Ukraine and Hetman Vyhovsky desperately needed the promised help.