From the very beginnings of the Church, the eucharistic celebration was in the center of its liturgical events. It was essential to take part in that celebration and to receive communion. At the same time, there was fervent faith in the real Christ's presence in the eucharistic forms of bread and wine, which were also kept after the mass, primarilv for the communion of the dying and the sick. The eucharistic bread and wine were always treated ,with exceptional respec't and goven the cult of latriae, attributed only to God, but, as late as the XI* century, there were no special outward forms of their observance. From the IV* century onward, the real connection between the mass sacrifice and communion gradually weakens, believers understand the mass with increasing difficulty, they resort to private piousness, and communion grows increasingly infrequent. This becomes more intensified in the Middle Ages. Christ's real presence in the eucharist becomes the centre of the believers' interest and their piousness, while the celebration itself and the essential purpose of that presence are pushed into the background. Believers want to see the host, they want to pay reverence and show respect to Jesus in the eucharist publicly. That's why the host is raised and various popular celebration appear, like the celebration of Christ's Body and Blood, precessions, where there is much exaggeration and . abuse. Protestant reaction develops. The Trent Council and the popes after it, especially the ones of the XX* century, defend the traditional eucharistic church doctrine, they encourage and tolerate variuos forms of eucharistic piousness, preventing exaggeration. Pope Pius X. encourages frequent, everyday communion and early communion of children. Pius XII. continues in a similar way. The Second Vatican Council puts the eucharist in the centre of the Church's liturgical life and lays the foundations of its right and theologically founded observance. Paul VI., in his Encyclical letter Mysterium Fidei, presents and confirms the traditional faith of the Church, but not even in this Encyclical letter can we find an integral and complete church doctrine about the eucharistic mystery. We shall find it only in the post-council documents. In the end, the author critically warns that, because of the present lack of complete and correct theology of eucharistic mystery, it is necessary to enrich the eucharistic piety and to put it on the right theological foundations, where the eucharistic celebration is the centre of ali forms of eucharistic piety. Such solutions are ensured by the postcouncil eucharistic documents.