Radiotherapy is commonly used in Ewing's sarcoma and pediatric soft-tissue sarcomas. In Ewing's sarcoma, radiotherapy appears to produce survival rates similar to surgery if used to treat the primary lesion, though the data remain subject to interpretation. When surgery is used to treat the primary lesions, postoperative irradiation should be given if the margins are less than wide, though the response to chemotherapy may also influence local control. In nonrhabdomyosarcoma soft tissue sarcomas, postoperative irradiation should be given if the margins are less than wide, with doses of 54 Gy at 1.8 Gy per day; this provides excellent local control.