Neuroblastoma (NB) is a rapidly growing, well-vascularized childhood cancer that often presents with metastases. The overall five-year survival in NB is approximately 45% despite multimodality treatment, and therefore there is a clinical need for new therapeutic strategies. NB frequently overexpresses the angiogenic factor VEGF (vascular endothelial growth factor). The aim of this study was to investigate the effect of bevacizumab (Avastin, Genentech/Roche), a humanized anti-VEGF-A antibody, on NB growth in three different xenograft models, chosen to resemble high-risk NB. The human NB cell lines SK-N-AS, IMR-32 and SH-SY5Y, which are poorly differentiated and overexpress VEGF-A, were injected s.c. in immunodeficient mice. Bevacizumab was given intraperitoneally twice weekly at 5 mg/kg body weight, starting at a tumor volume of 0.3 mL. Bevacizumab significantly (p < 0.01-0.05) reduced NB growth in vivo without toxicity by causing a 30-63% reduction of angiogenesis, but had no effect on NB cell survival in vitro. Serum concentrations of VEGF-A increased two- to six-fold during bevacizumab therapy which did not result in faster tumor growth compared with control animals. Based on our experimental data we suggest consideration of bevacizumab in treatment of high-risk NB that does not respond to conventional therapy and that overexpresses VEGF.