The true cementoma (attached cementoma) is an unusual benign jaw neoplasm fused to the root of the involved tooth. The authors have treated a true cementoma occurs at the right mandibular first molar. The 26 years old male patient who has complained of sweeling and discomfort of the involved tooth. The radiograph showed that the tumor represents a dense radiopacity bordered by a well demarcated peripheral radiolucent zone. Treatment was performed by extraction of the involved tooth with complete enucleation of the tumor. So the operation was done without any complications.