Two hundred fourteen eligible patients with previously untreated, localized Ewing's sarcoma of bone were randomized on IESS-II to receive Adriamycin (ADR; doxorubicin; Adria Laboratories, Columbus, OH), cyclophosphamide, vincristine, and dactinomycin by either a high-dose intermittent method (treatment [trt] 1) or a moderate-dose continuous method (trt 2) similar to the four-drug arm of IESS-I. Patient characteristics (sex, primary site, type of surgery) were stratified at the time of registration; these and other patient characteristics (age, time from symptoms to diagnosis, race) were distributed similarly between treatments. Surgical resection was encouraged, but not mandatory. Local radiation therapy was the same as for IESS-I. The median follow-up time is 5.6 years. The overall outcome was significantly better on trt 1 than on trt 2. At 5 years, the estimated percentages of patients who were disease-free, relapse-free, and surviving were 68%, 73%, and 77% for trt 1 and 48%, 56%, and 63% for trt 2 (P = .02, .03, and .05, respectively). The major reason for treatment failure for both treatment groups was the development of metastatic disease. The lung was the most common site of metastases followed by bone sites. The combined incidence of severe or worse toxicity (67%) was comparable between the treatments; however, severe or worse cardiovascular toxicity was significantly greater on trt 1. Tne only treatment-associated deaths (N = 3) were on trt 1 and were cardiac-related.