Angiogenesis depends on the adhesive interactions of vascular cells. The adhesion receptor integrin alpha(v) beta(3), was identified as a marker of angiogenic vascular tissue. Integrin alpha(v) beta(3), was expressed on blood vessels in human wound granulation tissue but not in normal skin, and it showed a fourfold increase in expression during angiogenesis on the chick chorioallantoic membrane. In the latter assay, a monoclonal antibody to alpha(v) beta(3), blocked angiogenesis induced by basic fibroblast growth factor, tumor necrosis factor-alpha, and human melanoma fragments but had no effect on preexisting vessels. These findings suggest that alpha(v) beta(3) may be a useful therapeutic target for diseases characterized by neovascularization.