Agnes, whose name means “chaste” in Greek, was a beautiful young girl of wealthy family and therefore had many suitors of high rank. Tradition holds that the young men, slighted by Agnes' resolute devotion to religious purity, submitted her name to the authorities as a follower of Christianity.
The Prefect Sempronius condemned her to be dragged naked through the streets to a brothel. As she prayed, her hair grew and covered her body. It was also said that all of the men who attempted to rape her were immediately struck blind. The son of the prefect is struck dead, but revived after Agnes prayed for him, causing her release. There is then a trial from which Sempronius excuses himself, and another figure presides, sentencing her to death. When led out to die she was tied to a stake, but the bundle of wood would not burn, or the flames parted away from her, whereupon the officer in charge of the troops drew his sword and beheaded her, or, in some other texts, stabbed her in the throat. It is also said that the blood of Agnes poured to the stadium floor where other Christians soaked up the blood with cloths.
Agnes was buried beside the Via Nomentana in Rome. A few days after Agnes' death, her foster-sister, Saint Emerentiana, was found praying by her tomb; she claimed to be the daughter of Agnes' wet nurse, and was stoned to death after refusing to leave the place and reprimanding the pagans for killing her foster sister. Emerentiana was also later canonized. One night when the parents of the blessed Agnes were watching at her grave, she appeared to them in company with a band of virgins, and said to them: Father and Mother, weep not for me as though I am dead; for now these virgins and I live together in him whose love was my whole life upon earth. Some years afterwards, Constance, the daughter of the Emperor Constantine, being sick of an incurable ulcer, betook herself to the said grave, although she was not yet a Christian, and as she lay by it and slept, she seemed to hear the voice of Agnes, saying to her: Constance, be of good courage: believe in Jesus Christ the Son of God, and he will make thee whole. The Princess, being healed, was baptized, along with many others of the Emperor's family and household, and afterwards built over the grave of the blessed Agnes a Church named in her honour.