Introduction: Aneurysmal bone cyst (ABC) is a non-neoplastic bone tumor of the skeletal system that occurs predominantly in children and young adults, accounting for 1–2% of all primary bone tumors. Any bone can be affected, but it uncommonly originates from the ribs. We present the case of a young girl with ABC arising from the 6th rib. Case Report: A 14-year-old girl was admitted to the Emergency Department with a 10-day history of gradually worsening leftsided back pain and swelling. The pain was constant and exacerbated by movement of rotating left upper hemithorax. She had no history of trauma or prior chest surgery, and her past medical history was unremarkable. A CT of the chest revealed lytic bone lesion at the 6th left rib. She underwent partial resection of the 6th rib with posterolateral incision without any need for reconstruction of the chest wall.Conclusion: Preoperative diagnosis of ABC could be difficult due to its rarity and the similarity with other lesions. Here, the essence of diagnosis is to exclude other causes, but the definitive diagnosis and treatment can be performed after en bloc resection. Although a rare cause of rib tumor, ABC should be kept in mind