Perhaps the best-known of the pre-communion prayers:
I believe, O Lord, and I confess that You are truly Christ, the Son of the Living God, who came into the world to save sinners, of which I am the first. Also I believe that this is Your sacred Body and this is Your precious Blood. Moreover, I pray to You to have mercy on me and pardon my transgressions, voluntary and involuntary, in word and deed, in knowledge or in ignorance. Make me worthy to partake without condemnation of Your sacred Mysteries, for the remission of sins and for everlasting life. Amen.
O Son of God, admit me today as a participant to Your Mystical Supper, for I will not speak of the Mystery to Your enemies. I will not kiss You as Judas did, but like the repentant thief, I will confess to You: Remember me, Lord, in Your Kingdom.
Let not the communion of Your holy Mysteries be toward judgement or condemnation, but for the healing of my soul and body. Amen.