344 previously untreated patients, under 19 years of age, with soft tissue sarcoma (STS) entered the first German STS Study, CWS-81. 218 of them with chemosensitive STS (Group A: rhabdomyosarcoma [RMS], synovial sarcoma, extraosseous Ewing's sarcoma, undifferentiated sarcoma and malignant peripheral neuroectodermal tumor) were evaluable for this analysis after a minimum potential follow-up of 6 years. A staging system based on the extent of disease, defined post-surgically, was used. The chemotherapy for stages I-III (VACA cycle) consisted of vincristine, dactinomycin, cyclophosphamide and doxorubicin. Patients with metastatic disease as well as stage III patients who failed to respond to VACA, were given ifosfamide instead of cyclophosphamide. The definitive local tumor control procedure for patients in stages II-III depended upon the tumor status at second-look surgery after 16 weeks of chemotherapy (no irradiation, 40Gy or 50Gy). The DFS rate after 5 years for group A was 57 +/- 4% and for patients with non-metastatic tumors (Stages I-III), 69 +/- 4%. There was no difference in prognosis between stages I and II (DFS rate 88 +/- 5% and 88 +/- 6% respectively). The DFS rate for stage III was 54 +/- 5% and for stage IV, 11 +/- 5%. Lack of local tumor control was the main cause of therapy failure: 10% of patients with localized disease never achieved CR, 18% relapsed locally. The most important prognostic factors were tumor size (p = .0002) and the degree of tumor regression after primary chemotherapy (p = .02).(ABSTRACT TRUNCATED AT 250 WORDS)