Blessed Egidio was a revered Catholic friar who lived in Basilicata (southern Italy) between the 15th and 16th centuries A.D. His natural mummy is preserved in the Mother Church of Laurenzana, the village where he lived. During the recent restoration and conservation of the relic, palaeopathological analysis was carried out. This revealed osteolytic lesions that affected the maxillary bones, as two injuries that were different in morphology and size that distinctly afflicted the right and left maxillae. The macroscopic and radiographic appearance of the lesion on the right maxilla and its proximity to the right premolar tooth that showed periapical granuloma suggest a diagnosis of an inflammatory odontogenic cyst (radicular cyst). The second lesion, of the left maxilla, was non‐specific and might have been the consequence of an inflammatory process. Odontogenic cysts are common in modern human populations but have been poorly described to date in ancient populations. The case of Blessed Egidio represents a new and rare case diagnosed in the field of palaeopathology.