Agnes may have been only 12 or 13 when she died a martyr’s death in Rome. According to tradition, she refused to consider marrying and consecrated her maidenhood to God.

When a persecution broke out, she left home and offered herself for martyrdom, probably dying by being stabbed in the throat, a common form of Roman execution.

She was buried in a cemetery on the Via Nomentana, where a church honoring her was built about 350. Her name and feast date were listed in a calendar of martyrs in 354.

She is patroness of girls and St. Agnes Parish and School in Phoenix.