Understanding of the molecular mechanisms of tumor development has increased considerably in recent years. As a consequence, the development of targeted therapies has proceeded rapidly, contributing to new drugs against cancer which are now under clinical investigation. Among these new therapies, anti-angiogenic drugs are of particular importance because they can be used against many different types of cancer. This is due to the fact that tumor angiogenesis seems to be involved in most if not all solid metastasizing malignancies.   The first part of this book summarizes the knowledge acquired on the molecular entities that play a role in tumor angiogenesis and their mechanisms of action. Furthermore, the identification of molecular markers and their validation as predictive and/or prognostic tools is reviewed. In the second and most important part, the clinical applications of anti-angiogenic treatments are documented for a wide variety of tumors. In particular, the modes of combination with other targeted and/or cytotoxic cancer therapies are presented.