Description: Supernumerary tooth with mirror-image on monozygotic twins Patient A, male, non relevant medical record. Intraoral examination reveals the presence of a conoid shaped supernumerary tooth, erupted between teeth 52 and 51. Patient B, male, monozygotic twin of previous patient, non relevant medical record. Intraoral examination showed the presence of an erupted supernumerary tooth, with a conoid morphology, located between teeth 62 and 61. The supernumerary tooth is fused with the central incisor. In both cases, radiographic exams reveal a normal root anatomy of the supernumerary teeth, but the overlapping anomaly is only present in one of the siblings. Discussion: This clinical case demonstrates that monozygotic twins may share similar dental anomalies. In this case, the coincidence of anomalies of number was observed, such as the presence of a supranumerary tooth in the pre-maxillary region, with a similar morphology and a symmetric distribution, suggestive of a mirror-image. The mirror-image phenomenon in monozygotic twins is described in the literature. Published data suggests that approximately 25% of this population manifests this characteristic, typically connected with tissues of ectodermic origin. It is believed that the presence of phenotypical discordances in identical twins may be the result of epigenetic influences during development. Conclusions: The dental anomalies described here, although rare, when diagnosed in a child with a monozygotic twin, constitute a find which warrants a screening of the same pathology on the twin. Keywords: Dental anomalies, fusion, supernumerary tooth, monozygotic twins, mirror image