Giant cell tumors (GCTs) are rare neoplasms, most commonly arising in the metaphysis/epiphysis of long bones. They consist of multinucleated giant cells with surrounding spindle-shaped mononuclear stromal cells. GCTs rarely appear in the ribs. We report a case of a GCT originating from the anterior arc of the fourth rib in a 31-year-old man who presented with a progressively growing thoracic mass in the left anterior chest wall. Thoracotomy involving en bloc resection of the chest wall and tumor and a reconstruction of the chest wall were performed.