This article aims to provide an insight into the ecumenical work of a Hungarian Benedictine monk, Gellért Békés. First, I offer a short overview of Békés's life, who was forced into exile by the socialist regime and who spent almost half a century as Professor at the University of Saint Anselm in Rome. Next, I review Békés's publications and the main thrust of his thinking in the field of ecumenical theology. The central part of my article is devoted to the presentation of his Italian monograph (Eucaristia e chiesa, 1985), which can be considered to be his most important work and in which he gives a comprehensive account of his ecumenical theology of the Eucharist, especially in the light of the Lima Document of 1982. His major contribution lies in the fact that he took into account the interrelation between the various ecumenical documents and he integrated the newly retrieved dimensions of the Eucharist. He also commented on the idea of Real Presence developed by the Lima Document in the light of Catholic doctrine. Last but not least, this article wants to contribute to the reception of Békés's thought, which has hardly begun even in his own country.