Fifty-two children with favorable histology Wilms' tumor who had residual abdominal disease (Surgical Stages III and IV) were treated from 1979 to 1988 on a protocol designed to assess the effectiveness of reduced radiation doses. All patients received three-agent chemotherapy, beginning within 1 week after surgery. To permit assessment of disease response to initial chemotherapy, radiation therapy was delayed for a median of 28 days after surgery (range, 14-71 days). Total doses of abdominal radiation were limited to 12 Gy, given as 150 cGy daily fractions; 18 patients with Stage IV disease received 12 Gy bilateral pulmonary irradiation. Two year disease-free survival was 85% and 71% for Stage III and IV, respectively (p = .24). Abdominal relapses occurred in 3 cases (5.7%). The interval between surgery and initiation of irradiation was not related to disease-free survival. Of several patient and disease-related factors analyzed, only patient age was related to outcome. Disease-free survival was 100% at 3 years for children under the age of 3 versus 78% for children greater than age 3 (p = .05). Reduced-dose abdominal radiotherapy in conjunction with multi-agent chemotherapy and surgery provided excellent disease control with minimal toxicity in advanced-stage, favorable histology Wilms' tumor.