Recent studies have revealed that a number of gene products such as vascular endothelial growth factor and its receptors are deeply involved in the process of angiogenesis. Most of these genes were characterized not only by the biochemical/molecular biological approach but also by the genetical approach including the use of gene-targeted mice. Furthermore, some of these genes are strongly correlated with the formation of pathological blood vessels such as tumor angiogenesis, suggesting that these gene products are good candidates for screening anti-angiogenic materials. Inhibitors against VEGF and its receptors have been most extensively studied and developed, but inhibitors to other factors such as MMPs and angiopoietins may also be useful for developing anti-angiogenic materials. In addition to these molecules, unidentified gene products could be specifically involved in certain types of pathological angiogenesis.