To evaluate the prognosis of patients with Wilms' tumor who have pulmonary densities identified on a computed tomographic (CT) scan of the chest, but have a negative plain chest radiograph, we reviewed the treatments and outcome of 32 patients randomized or followed on National Wilms' Tumor Study (NWTS)-3. The 4-year event-free and overall survival percentages of 18 of these patients who had a favorable histology tumor and were treated as stage IV tumors with three or four drugs plus whole-lung irradiation were 88.1% and 94.0%, respectively. The 4-year event-free and overall survival percentages for nine favorable histology patients treated less aggressively based on the extent of locoregional disease with two or three drugs and without whole-lung irradiation were 88.9% and 88.0%, respectively. There were no statistically significant differences in the 4-year event-free or overall survival percentages between the two groups. The current data do not demonstrate improved survival for favorable histology patients treated with whole-lung irradiation for pulmonary metastases identified only on chest CT scan. However, due to the small number of patients included, no statistically valid conclusions regarding the roles of Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH) and/or whole-lung irradiation in the treatment of these patients can be drawn from the present analysis. Additional patients need to be systematically studied to determine if these preliminary observations can be confirmed.