Twenty-one patients with pathologically proven Ewing sarcoma without overt metastases at diagnosis were treated with a protocol designed by the Royal Marsden/St. Bartholomew's Hospitals Children's Solid Tumour Group (CSTG). They received megavoltage radiotherapy to the involved bone and adjuvant chemotherapy with a combination of four cytotoxic drugs. Seven patients have so far relapsed, four at the original site and three in other bones. The other 14 are clinically free of disease a median of 36 months from diagnosis. Comparison with a historical control group of 19 patients treated with surgery or radiotherapy, but without initial chemotherapy, shows a significant improvement in survival for the study group (P = 0.03). Seventeen of the controls have died. The treatment regime was moderately toxic, but there were no treatment-related deaths. These results confirm that an improved survival time and hopefully cure rate can be expected from treating Ewing tumour with high doses of megavoltage radiation and combination chemotherapy. Future goals must be the better control of large primary lesions and the eradication of micrometastases in other bones. The place of surgery should be re-evaluated in the treatment of the primary tumour, and better adjuvant chemotherapy regimes are needed.