Purpose The overall survival (CIS) of patients with relapsed Ewing's sarcoma family of tumors (ESFT) is poor, and the relative benefit of high-dose therapy (HDT) is controversial. Patients and Methods We retrospectively identified 55 consecutive ESFT patients with adequate medical records for review, who were treated at Children's Hospital and Regional Medical Center and who developed disease recurrence between January 1, 1985 and December 31, 2002. Results The median relapse-free interval (RFI) from diagnosis to first recurrence was 17 months (range, 5 to 90 months). Most recurrences were metastatic only (39 patients) or local and metastatic (10 patients). Twenty-seven patients (49%) achieved a partial or complete response to second-line treatment, with a median duration of response of 27 months (range, 5 to 119+ months). The 5-year CIS rate for all relapsed patients was 23% (95% CI, 11 % to 35%). By univariate analysis, improved OS was associated with response to second-line treatment versus no response (46% v 0%, respectively; P < .0001), RFI >= 24 months versus less than 24 months (48% v 12%, respectively; P = 0001), and no metastases at initial diagnosis versus presence of metastases (31 % v 12%, respectively; P = 05). Because all 13 patients who received HDT also had responsive relapse, we performed a multivariate analysts. Reduced risk of death was associated with response to second-line therapy (relative risk, 0.14; 95% CI, 0.05 to 0.40), RFI >= 24 months (relative risk, 0.29; 95% CI, 0.13 to 0.66), and receiving HDT (relative risk, 0.26; 95% CI, 0,08 to 0.85), Conclusion HDT as consolidation therapy for relapsed ESFT seems to be associated with improved OS, even after adjusting for RFI and response to second-line treatment. (c) 2005 by American Society of Clinical Oncology.