Vascular endothelial growth factor (VEGF) and its related member, placental growth factor (PlGF), play important roles in stimulating vascular growth (angiogenesis) in both physiological conditions such as embryonic development and pathological conditions such as inflammation and tumor growth. Development of monoclonal antibodies (MAbs) capable of blocking the interaction of VEGF and its receptors, which in turn block VEGF-mediated angiogenesis, has become a novel and very powerful approach for cancer management. Here we report the generation of a mouse monoclonal antibody M23, which binds to both the natural and denatured forms of human VEGF165, as well as to two other major VEGF isoforms (VEGF121 and VEGF189) being tested. MAb M23 does not bind to other VEGF-related proteins such as PlGF. This MAb will have great future potential in VEGF-related research, diagnosis, and treatment.