She lived in the earliest days of the Church, in the heart of Rome. She rejected fame, power, and even marriage — all out of love for God. For centuries, she was venerated as the daughter of Saint Peter, buried beside the apostles, invoked by kings and popes… and yet, over time, she was forgotten.
The story of Saint Petronilla is an invitation to rediscover hidden faithfulness, silent holiness, and the strength that comes from radical surrender. In this article, you’ll learn about the journey of this young Christian woman, the miracles associated with her, her relationship with Saint Peter, and why she is honored as the patroness against fevers — and of Christian France.
A Young Woman Consecrated to God
Petronilla lived in first-century Rome. Tradition tells us she was a beautiful young woman, of noble origin, with a promising future. But she made an unusual choice: she consecrated her entire life to God through a vow of virginity. In a society where marriage and motherhood were expected of every woman, her decision was seen as radical.
Her fidelity to that vow was put to the test when a powerful Roman nobleman named Flaccus asked for her hand in marriage. Petronilla refused. Flaccus, angered by the rejection, gave her an ultimatum: three days to change her mind. If she didn’t, he would take her by force. The young woman then fasted and prayed intensely. On the third day, she died peacefully — as if God had answered her prayer and taken her to Himself before her vow could be broken.
Her act was understood by the early Christians as a martyrdom of conscience. Though she wasn’t killed by human hands, she gave her life out of fidelity to Christ. And for that, she came to be venerated as a martyr.
Daughter of Saint Peter?
One of the most striking aspects of the tradition surrounding Petronilla is the title she received: daughter of Saint Peter. But what does that actually mean?
The Bible tells us that Saint Peter was married, but there’s no direct mention of children. Even so, many Church Fathers and early Christian communities believed that Petronilla was, in fact, Peter’s daughter. Why? Because according to ancient tradition, she was healed by Saint Peter from paralysis that had left her unable to walk. After this miracle, she became his closest disciple.
In the early Church, the one who baptized you was considered your spiritual parent. So Petronilla came to be called Peter’s daughter — not by blood, but by faith. Even her name — “Petronilla” — is a feminine diminutive of “Petrus” (Peter), further strengthening this symbolic connection.
Patroness Against Fever
The healing Petronilla received was never forgotten. Over the centuries, many faithful began invoking her in times of illness — especially in cases of high fever and debilitating diseases. She became known as the patroness against fevers, an intercessor for those who suffer both physically and spiritually.
This popular devotion grew particularly strong during the Middle Ages, when epidemics plagued Europe. In a time when medicine had few answers, the faithful turned to prayer and the intercession of the saints. Petronilla was invoked as someone who had known the fragility of the human body — and had overcome it through faith.
The Saint of the French Kings
Another curious and impressive fact: Saint Petronilla became the patroness of the French monarchy. This happened when the kings of France, in an effort to strengthen their alliance with the papacy, began to refer to themselves as the “adopted sons of Saint Peter.” Petronilla, as Peter’s spiritual daughter, was then symbolically recognized as the spiritual sister of France.
She was honored in royal Masses, venerated at French altars, and even had a chapel dedicated to her inside St. Peter’s Basilica — known as the Chapel of the French Kings. There, nobles prayed, celebrated liturgies, and some were even buried beside her relics.
A Forgotten Saint?
Over time, however, devotion to Saint Petronilla began to decline. In the Church’s liturgical calendar reform of 1969, her feast day — previously celebrated on May 31st — was replaced by the Feast of the Visitation of the Blessed Virgin Mary.
She was relegated to the Roman Martyrology, with only local commemoration. Many Catholics today have never heard her name — even though her body still rests within St. Peter’s Basilica, among the greatest saints of the Church. The saint once lovingly called “filia dulcissima” (“most beloved daughter”) by the popes is now a quiet voice, waiting to be heard again.
The Tomb and the Mystery
Saint Petronilla’s original tomb was located in the Catacombs of Domitilla in Rome. There, an ancient fresco was found bearing the inscription “Petronella Martyr.” This confirms that her veneration as a martyr dates back to the early centuries of Christianity.
In the 8th century, her relics were transferred to St. Peter’s Basilica. They were placed in a marble sarcophagus bearing the inscription: “Filiae dulcissimae” — “To the sweetest daughter.” Today, her exact burial site within the new Renaissance basilica is unknown, adding an air of mystery and quiet reverence to her presence.
Conclusion: A Holiness That Endures
Saint Petronilla is a powerful reminder that true greatness is not found in human recognition, but in quiet faithfulness. She chose God above all. She remained faithful, even unto death. And her story — filled with healing, courage, and surrender — still echoes, even today.
Perhaps you had never heard of her before. But now that you know her story, you can carry her name in your heart. And when the fevers of the soul — fatigue, anxiety, or doubt — knock at your door… remember Saint Petronilla. And ask for her intercession.
Saint Petronilla, pray for us.