Wilms' tumor is one of the most common solid tumors of childhood. Approximately 500 cases occur annually in the United States, and the overall incidence is 0.8 per 100,000 children per year. Direct involvement of the inferior vena cava occurs in 5% to 10% of cases. The National Wilms' Tumor Study (NWTS), an intergroup cooperative clinical trial, indicates that aggressive primary surgical management combined with chemo-radiation therapy improves (with respect to both survival and recurrence) the long-term prognosis for children who have extrarenal involvement. In addition, aggressive surgical resection may further improve the survival rate for patients with recurrent Wilms' tumor after initial multimodal therapy.