The biologic behavior of neuroblastoma (NB) is extremely variable; therefore, the clinical behavior may be reliably predicted based on the analysis of a panel of prognostic parameters. High vascular density has been correlated with aggressive tumor progression in many types of cancers. The goal of this study was to correlate the tumor vascularity in NB with status of MYCN and the short arm of chromosome 1 (1p) to address the association between angiogenesis and genetic markers of prognostic significance. The study population consisted of 33 patients with histologically proven diagnosis of primary NB and no history of previous chemotherapy. Histologic quantitation of tumor angiogenesis was performed using 3 different methods: microvessel density, vascular grading, and Chalkley counting. MYCN amplification and 1p deletion were determined by using fluorescence in situ hybridization technique. The differentiation and mitosis-karyorrhexis index of tumor cells were also assessed using the Shimada System. MYCN amplification was present in 12 cases (36.3%), and 1p deletion in 16 (48.5%). Both genetic changes significantly correlated with increased tumor vascularity. In addition, tumor vascularity was significantly increased in tumors with high mitosis-karyorrhexis index or of undifferentiated histology. We conclude that angiogenesis shows close association with histologic and genetic prognosticators in NB. Our data support the validity of recent applications of antiangiogenic agents which interfere or block NB progression.