The purpose of this study was to evaluate the outcome of patients with Ewing sarcoma (ES) of the pelvis, attempting to identify prognostic factors to select patients for more aggressive treatment. Seventy-seven patients with nonmetastatic ES of the pelvis were treated at Rizzoli Institute between 1979 and 1996. Four different protocols of chemotherapy were used successively. Two protocols consisted of VACAc, and two of VACAc plus ifosfamide and etoposide. Local treatment consisted of surgery in 5 patients, radiotherapy in 60, and surgery followed by radiotherapy in 12. Mean follow-up was 11 years (range 5-25 years). Thirty-three patients remained continuously free of disease; 43 relapsed (24 due to metastases and 19 to local recurrence and metastases); 1 died of treatment-related complications. The 5- and 10-year event-free survival rates were 45% and 44%, respectively, and the 5- and 10-year overall survival rates were 48 and 44. These results are significantly worse than the ones achieved in 329 contemporary patients with extrapelvic lesions treated with the same protocols of chemotherapy (5- and 10-year event-free survival = 46% vs. 64% and 44% vs. 69%). Thus, despite associated chemotherapy, the outcome of ES localized in the pelvis remains poor, and new innovative methods for the treatment of this tumor are needed.