The science
What the Church holds, and what science found
Short answers first, then the evidence and the sources.
Is incorruptibility a miracle?
No. The Catholic Church does not count the incorruption of a body among the miracles it examines for beatification or canonization, and it does not treat an incorrupt body as proof of holiness.
In the 1730s Prospero Lambertini, later Pope Benedict XIV, set out strict conditions under which the incorruption of a body could be treated as miraculous: no embalming or other deliberate preservation, and flexibility, color, and freshness that last for years. He wrote them in his treatise on beatification and canonization, book IV, part I, chapters 30 and 31.
The current norms for the causes of saints, issued in 1983, do not address incorruption, and no Vatican document rules on it directly. In practice modern causes do not count it as a miracle. In 2024 the Diocese of Kansas City-St. Joseph, writing about an exhumation in Missouri, said that incorruptibility "is not considered to be an indication of sainthood."
Sources: Benedict XIV, De Servorum Dei Beatificatione et Beatorum Canonizatione, book IV, part I, chapters 30 and 31. Joanne M. Pierce, The Conversation, 2023. Diocese of Kansas City-St. Joseph, August 2024.
What happens at a canonical recognition
A canonical recognition is the opening of a tomb or reliquary under the bishop's authority, to examine and record the remains.
- A tribunal of the bishop or his delegate, a promoter of justice, and a notary takes part, with a medical expert such as an anatomical pathologist and at least two witnesses.
- The experts sign a report on the state of the remains, and publicity is to be avoided.
- Any conservation is done with the bishop's consent, after which the body is recomposed and placed in a new urn.
- Images of these operations may not be published without the written permission of the bishop and the heir.
- Selling relics is absolutely prohibited.
Source: Congregation for the Causes of Saints, Relics in the Church: Authenticity and Preservation (2017), articles 8 to 19, 25, and 30.
How bodies are preserved
Most preserved bodies can be explained by one of four processes, and a case file names one only when an examination or a documented treatment supports it.
Natural mummification
The body dries out in dry, ventilated, or cold conditions and keeps its shape without any human treatment. St. Zita in Lucca was studied as a natural mummy.
Saponification
In damp, airless graves, body fat can slowly turn into a waxy substance, often called grave wax or adipocere, that holds the body's form.
Corification
A leathery preservation of the skin, described in bodies sealed inside metal coffins.
Embalming
Deliberate treatment, usually by injecting fluids. Pope St. John XXIII was embalmed in 1963, and the embalmer's formula for the child Rosalia Lombardo in Palermo was published in 2009.
Sources: A. C. Aufderheide, The Scientific Study of Mummies (Cambridge University Press, 2003). D. H. Ubelaker and K. M. Zarenko, Forensic Science International 208 (2011). D. Piombino-Mascali and others, Virchows Archiv 454 (2009), with a CT study in Annals of Anatomy 195 (2013).
Why some saints wear masks
When a face has darkened or decayed, custodians often cover it with a thin mask modelled on photographs, and sometimes cover the hands too. This record always says when one is present.
| Body | Covering | When | Made by |
|---|---|---|---|
| St. Bernadette | Wax face and hands | 1925 | The Pierre Imans firm, Paris |
| St. Catherine Labouré | Wax face | Not recorded here | An unnamed artist, from a photograph, according to the chapel |
| St. John Vianney | Face remade in wax | Not recorded here | Not recorded here |
| Pope St. John XXIII | Thin wax on face and hands | 2001 | Not named in the sources |
| St. Pio of Pietrelcina | Silicone mask | 2008 | Gems, a studio in London |
| St. Carlo Acutis | Silicone reconstruction of the face. The Bishop of Assisi said the body was found in the normal state of transformation. | At his translation to Assisi | Not named in the sources |
| Sister Wilhelmina Lancaster | Wax face mask and wax on the hands | 2023 | The sisters of her community |
The Orthodox view
The Eastern Orthodox tradition gives incorruption more weight than the Catholic one, though not uniformly.
Russian tradition took an incorrupt body as a sign of grace, while the Byzantine tradition did not require it. This record models every tradition from the start and adds the Orthodox incorrupt relics after the Catholic checklist is complete.
Source: A. Sulikowska-Bełczowska, Series Byzantina 14 (2016).
How we grade the evidence
The grade describes the evidence for a body's documented condition and treatment, not whether the body is truly incorrupt.
A claim contradicted by a well-documented examination takes the grade of that documentation, and the contradiction is stated in the claim.
By the numbers
How many incorrupt saints are there? No one knows, and every count depends on the list it comes from.
| Count | What it counts | Checked |
|---|---|---|
| 102 | Numbered entries in Joan Carroll Cruz, The Incorruptibles (TAN Books, 1977) | Publisher's contents |
| about 154 | Names on the largest list on the web, roman-catholic-saints.com, with no locations and no sources beyond Cruz | Sep 21, 2026 |
| about 99 | Pages in English Wikipedia's category of incorrupt saints, which is not curated | Sep 21, 2026 |
| 236 | Total claimed by Spanish Wikipedia's list, without a source, although the list itself has 38 rows | Sep 21, 2026 |
| 613 | Candidates in this draft register, gathered from about 300 sources in six languages and not yet verified | Sep 22, 2026 |
How the draft was built: 2,340 rows from lists, articles, and scholarly papers in English, Italian, Spanish, Portuguese, French, and German were matched across languages into one row per person. About 75 possible duplicates still need review, and every entry still needs checking against primary sources.