Odontogenic myxoma (OM) is a benign intraosseous tumor, but locally invasive, having a high rate of recurrence. It preferably locates in posterior mandibular regions, followed by the incisors, maxillary and; exceptionally, the mandibular condyle. Odontogenic myxoma can be found most often in young adults aged 25-35 years although lesions may occur over a lifetime, reporting the lowest prevalence in childhood with a predilection for permanent dentition. This paper presents a case of a three-year-old boy who visits the dentist because some mandibular teeth have not erupted. Panoramic radiograph and CBCT exams were performed. The tumor was radiological and histologically diagnosed as odontogenic myxoma. It was decided to do conservative surgery and it has been controlled for 4 years with favorable results and without imaging signs of relapse. This case demonstrates the unpredictability of a pathological maxillo-facial lesion, and leads to suggesting early control of the dental development process in pediatric patients.