Sequential half-body irradiation (HBI) to be delivered in two sessions was used in 18 consecutive patients with metastatic Ewing sarcoma who relapsed after radiotherapy and multidrug chemotherapy. The HBI program to both upper and lower hemi body was completed in 11 patients (61%). The remaining 7 patients received only one single treatment of HBI because of relapse before the completion of the treatment program. In 20 of the 29 sessions HBI was employed to treat overt metastases. The overall objective response rate was 50%. Six of 18 patients (33%) are alive from 4 to 27 months, 3 of them without evidence of disease. No severe toxicity was observed. HBI as systemic treatment was more effective in patients who relapsed while off chemotherapy, with metastases confined to the lungs or to one single bone segment.