The evaluation and treatment of primary bone malignancies in children have evolved considerably over the past decade, with a measurable improvement in prognosis. Disease-free survival has improved mainly due to intensive multiple-agent chemotherapy, refinement in radiotherapeutic techniques, better imaging, and wide surgical resection. Reconstruction techniques after “limb-sparing” surgery have used allograft, composite allograft-prosthesis, or “expandable” prostheses reconstruction after adequate removal of the tumor with wide margins. The diagnosis and understanding of these tumors has also improved with advances in molecular genetics. Both osteosarcoma and Ewing's sarcoma treatment have undergone this dramatic change; recent advances in molecular genetics, treatment, magnetic resonance imaging, and “limb-sparing” surgery are highlighted.