Vascular endothelial growth factor (VEGF) has been shown previously to correlate with tumor growth and metastasis in an experimental model of anaplastic Wilms' tumor. The authors hypothesized that treatment with anti-VEGF antibodies would suppress both primary tumor growth and metastasis in this model. Tumors were induced in the right kidneys of nude mice by the injection of cultured Wilms' tumor cells. After 1 week, anti-VEGF treatment was begun with injection of either vehicle or an anti-VEGF antibody intraperitoneally. Mice were killed after 4.5 weeks of treatment and tumor weights and the incidence of metastases evaluated. Anti-VEGF treatment resulted in a greater than 95% reduction in tumor weight (P <.0001). Anti-VEGF treatment also abolished the establishment of lung metastases (40% in control animals, P <.003). Cessation of treatment resulted in rebound tumor growth. Anti-VEGF therapy can suppress both primary tumor growth and the establishment of metastases in experimental anaplastic Wilms' tumor.