The absence of her name from the 4th-century Roman calendar of feasts suggests that Petronilla died at the end of the first or during the 2nd century, since no special feasts for martyrs were celebrated during this period. After the erection of the basilica over her remains and those of Sts. Nereus and Achilleus in the 4th century, her cult extended widely and her name was therefore admitted later into the martyrology. A legend, the existence of which in the 6th century is proved by its presence in the list of the tombs of the Roman martyrs prepared by Abbot John at the end of this century, regards Petronilla as a real daughter of Saint Peter. In the Gnostic apocryphal Acts of St. Peter, dating from the 2nd century, a daughter of St. Peter is mentioned, although her name is not given.