Dentigerous cysts are the second most common odontogenic cysts and generally associated with the crowns of impacted or unerupted permanent teeth. The teeth most frequently affected are the mandibular third molars and the maxillary canines. Only 5% of dentigerous cysts are related to supernumerary teeth. The purpose of this report is to present a case of dentigerous cyst with a mesiodens in a 6-year-old male. The patient was treated by surgical enucleation of total cyst and extraction of impacted mesiodens under general anesthesia.