Supernumerary tooth is a rare event, which is usually found coincidentally in radiographic examination. The prevalence of this event is 1-3% with different prevalence for primary and permanent dentition. Supernumerary teeth may cause various clinical problems including: delayed or failure of eruption, displacement or rotation of permanent teeth and cyst formation. The purpose of this study was to present the case of a 9-year-old boy who had a large dentigerous cyst around his primary mandibular left premolar that was enucleated with the tooth. A year after this enucleation, we have observed a supernumerary tooth in mesial of canine. It is a reasonable question that “can the supernumerary tooth formation relate to the dentigerous cyst around impacted tooth?” Therefore, it is necessary to perform more pathological investigation in this aspect to answer this question.