Sister Saint-Hilaire (born Marie Petit) was a French religious of a teaching congregation of the Lyon region. She had suffered for several years from a severe chronic gastrointestinal disease — with intractable vomiting and severe weight loss reducing her to a state of cachexia. Multiple physicians had judged the condition irreversible.
She came to Lourdes on the August 1904 national pilgrimage — the same pilgrimage that produced several other recognised cures of the Pius X cluster (Marie-Thérèse Noblet, Sister Sainte-Béatrix, Johanna Bezenac). She was bathed in the piscines on August 22, 1904 and was instantly cured — the vomiting ceased, normal nutrition resumed, and she regained the lost weight over the following months. The cure was followed for years by the Lourdes Medical Bureau and was recognised by the Cardinal Archbishop of Lyon among the cures of the official Lourdes list.