EN
This article presents connections between the Polish - Ukrainian dialogue and reconciliation with historical forms of ecumenical aspirations, which arose on the Ruthenian territory of the First Republic of Poland. It is a look at the past which seeks inspiration and arguments in support of the inclusion of the Orthodox Church into the Polish-Ukrainian dialogue. This dialogue should be this way balanced and broadened. Because so far, it has been mainly led within the Catholic Church of the Latin rite and the Byzantine-Ukrainian Church. This article points out several examples of how and where the ecumenical potential of the Polish-Ukrainian dialogue can be spotted. These examples are connected with: [1] universalist understanding of the sacrament of baptism on the Polish-Ruthenian borderland in the Middle Ages, [2] ecumenical thought of the Reverend Stanislaw Orzechowski, [3] teaching about sacraments of baptism and marriage administered in the Catholic Church and the Orthodox Church of Piotr Mohyla.