The results of treatment in twenty-seven patients who had a Ewing sarcoma of the pelvis were reviewed. Six patients had had metastatic disease at the time of the diagnosis. The three-year actuarial survival of these patients was 17 per cent (95 per cent confidence interval, 8 to 52 per cent). Of the twenty-one remaining patients, thirteen had received chemotherapy and radiation therapy to the primary lesion and eight had had chemotherapy and operative resection, with or without radiation therapy. The actuarial five-year over-all survival was 25 per cent (95 per cent confidence interval, 6 to 51 per cent) in the group that had had radiation without a resection and 75 per cent (95 per cent confidence interval, 31 to 93 per cent) in the group that had had a resection (p < 0.005, log-rank method). The actuarial over-all five-year survival was 45 per cent (23 to 65 per cent) for all patients who had had localized disease when first seen. Actuarial local failure analysis (the censoring of patients who died without evidence of local failure before the two-year follow-up examination) revealed a rate of local failure of 44 per cent (14 to 79 per cent) in the group that had been treated with chemotherapy and radiation alone compared with 13 per cent (0 to 53 per cent) in the patients who had had a resection, but this difference was not significant (p > 0.25, log-rank method).(ABSTRACT TRUNCATED AT 250 WORDS)