ABSTRACTDentigerous cyst is a type of odontogenic cysts and generally occurs in the ages of twenties or thirties. Dentigerous cyst always includes a tooth which cannot complete the eruption process and occurs around the crown by the fluid accumulation between the layers of enamel organ. In rare cases, dentigerous cyst occurs in the first decade of life and develops in an immature permanent tooth as a result of a chronic inflammation of overlying nonvital primary tooth. In this report, a case of dentigerous cyst in primary dentition in a 5-year-old child patient and its treatment were presented. The dentigerous cyst was totally enucleated, and the unerupted permanent first premolar tooth was removed from the primary mandibular right premolar region. There was no recurrence observed after 18 months follow-up.