Based on the analysis of the attitude of the Bishop of Krakow, Zbigniew Oleśnicki, towards the Polish-Lithuanian Union, the author comes to the conclusion that the opinion expressed in historiography that he pursued his own Lithuanian policy is groundless. From 1429, Oleśnicki was one of the main executors of the most important political decisions in the Crown of the Kingdom of Poland, which resulted from the cooperation of the king and his advisors. There is little specific information that can be said about Oleśnicki's personal views on the functioning of the Union at that time. They are expressed only as his influence on the political life of the state increases after 1434. From the available source material, it can be assumed that Oleśnicki was determined to continue the policy developed under Jagiełło. It was based on the assumption that the Polish Crown must maintain the union with Lithuania at all costs - even at the expense of extensive concessions to the Grand Duchy.