Aneurysmal bone cysts are not real cysts or aneurysms; they are rare non-neoplastic bone lesions. Although aneurysmal bone cysts occur mainly in the long bone metaphyses, they are rarely seen in the facial bones. In the jawbones, the mandible is involved more commonly than the maxilla. It is mainly seen in the first and second decades. Aneurysmal bone cyst affecting the left mandible of a 10-year-old male patient is presented in this case report. The diagnosis of aneurysmal bone cysts is essential and appropriate treatment should be done considering various factors such as age, surgical complications, and the possibility of recurrence.