Angiogenesis, the process by which new blood vessels are formed from preexisting vessels, is essential for growth and progression of solid tumors. A number of growth factors regulate angiogenesis, but vascular endothelial growth factor (VEGF) is the most important. Activation of the VEGF pathway triggers a range of signaling processes, stimulating vascular endothelial cell growth, migration, survival, and permeability. VEGF is expressed by most human cancers and its expression often correlates with tumor progression and poor prognosis. In contrast, VEGF plays a limited role in adult physiological angiogenesis, making it an ideal target for therapeutic agents designed to inhibit tumor angiogenesis. Disruption of VEGF signaling can occur through inhibition of the VEGF ligand or receptors, and preclinical models have shown that VEGF and VEGF receptors are viable targets for antiangiogenic agents.