The Blessed Sacrament is a devotional name used by Roman Catholics to refer to a consecrated host, that is, a communion wafer which Catholics believe has actually become the body and blood of Jesus at the moment of the Consecration during the Liturgy of the Eucharist at Mass.

The Blessed Sacrament may be received by Catholics who have undergone their First Holy Communion (ie., given by a priest or other Minister of the Eucharist to a Catholic and swallowed by the communicant) as part of the Liturgy of the Eucharist during Mass.

It can also be exposed (displayed) on an altar in a Monstrance. Rites involving the exposure of the Blessed Sacrament include Benediction and Perpetual Adoration. The adoration does not involve the adoration of the host but of Christ, who in Catholic theology, is believed to be transubstantiated in it. A majority of Protestants would argue that this is the precise definition of what an idol is and why an idol is worshipped— for the spirit embodied within it, though a Monstrance may be displayed on the altar in some Anglican communions.