Primary giant cell tumors of the chest wall are extremely rare. To date, we believe that there have been no reported cases of sternal giant cell tumors in the thoracic literature. We report a case of an isolated giant cell tumor of the sternum in a 28-year-old man. The mass was resected and the sternum was reconstructed with methyl methacrylate prosthesis and bilateral pectoralis muscle advancement flaps. Excellent functional and aesthetic results were achieved.