Wilms' tumor is the most common malignant tumor of the urinary tract in children but is rare in adults. Although histologically the tumors appear to be the same, successful treatment with multimodal therapy is much more common in childhood. We report on 2 patients with adult, anaplastic, Stage IV Wilms' tumor, one of which was discovered during pregnancy and was managed successfully with chemotherapy, including ifosfamide, carboplatinum, and etoposide. As more patients are properly identified and treatment outcomes with chemotherapeutic regimens documented, better therapeutic approaches in adult Wilm's tumor will be developed, resulting in improved survival.