Angiogenesis is a complex process likely to be subject to many levels of regulation. Advances in understanding these controls are making it easier to formulate strategies aimed at inhibiting new vessel growth. The destruction to tumor tissue is exponentially related to the reduction in vascularization. Because the tumor cells are actively proliferating and dependent on continued vascularization, any mechanism that interferes with the proliferation of new vessels will interfere with tumor growth. The destruction or prevention of each capillary segment led to death or inhibition of thousands of tumor cells. The only event that stands between maintenance of metastatic cells in a dormant state and their establishment into a secondary tumor is the development of a vasculature. Thus, therapies aimed at interfering with vascularization represent viable strategies for antimetastasis.