Angiogenesis, the formation of new blood vessels from preexisting microvasculature, is a highly regulated process. Angiogenesis is controlled by both positive and negative factors thus providing several targets for drug discovery. The inhibition of angiogenesis represents a new approach to cancer therapy and several agents and approaches are in different stages of clinical development. These inhibitors were recently shown to constitute a new modality for cancer treatment. In this article, we will review angiogenesis inhibitors-related patent literature for the years 2000-2005. This review will cover specifically the discovery and development disclosures of endogenous inhibitors. The scope of this review is to give the reader a well-structured patent literature review of these agents targeting different steps of the angiogenic process. Finally, we have summarized the key attributes of the emerging endogenous angiogenesis inhibitors that make them potent antitumor agents.