The treatment of pediatric bone malignancies has undergone dramatic change in the past two decades. With the use of adjuvant chemotherapy, survival of patients with osteosarcoma and Ewing's sarcoma has greatly increased and most extremity lesions are now managed with an initial course of chemotherapy followed by limb-sparing surgery rather than amputation. Radiologists are called on not only to help diagnose and stage these tumors, but also to assess their extent, to determine response to preoperative chemotherapy, and to monitor patients for postoperative complications and recurrent disease. This article discusses imaging solutions to clinical issues that arise during the care of these children.