The purpose of the article is to explore the crisis period in the Ukrainian-Polish relations in the Galician Sejm at the beginning of the 20th century and the participation of Oleksandr Barvinskyi in these events. Research Methodology. The study employs general scientific comprehensive research methods (empirical, comparative, theoretical, and analytical methods). Throughout the research, the author adheres to the principles of historicism, objectivity, and systematicity, ensuring that the analyzed sources and historiographical material are reliable and representative. The scientific novelty of the article lies in attempting a comprehensive analysis of Oleksandr Barvinskyi’s position during the secession of Ukrainian deputies of the Galician Sejm in 1903. Conclusions. The article traces that Oleksandr Barvinskyi’s participation in the secession of Ukrainian deputies from the Galician Sejm in 1901 proved to be a key stage in his political activity, determining a decisive turn in his approach to Ukrainian-Polish relations and political interaction. It has been clarified that initially, O. Barvinskyi defined his tactics as compromising and aimed at achieving Ukrainian aspirations through participation in parliamentary processes. However, the events of 1901, including the adoption of the bill on rental housing and the escalation of ethnic conflicts, forced him to reconsider his position. The secession reflected a break with the policy of compromise and demonstrated the evolution of the ideological platform of the socio-christian movement. Initiated by a sense of failure in negotiations with the Poles, the secession became an expression of a decisive defense of Ukrainian interests and a refusal of compromises that evidently did not yield the expected results. The 1901 secession determined the course of events in Galicia, emphasizing the need for Ukrainian political independence and intensifying the struggle for the rights and interests of Ukrainians. In conclusion, Barvinskyi’s participation in the secession defined a new stage in his political activity, pointing to the necessity of a more active and resolute advocacy for the rights and interests of Ukrainians in Galicia.