Bispecific binding molecules, in particular immunoglobulin single variable domains such as VHHs and domain antibodies, comprising a VEGF-binding component and a Dll4-binding component in one molecule. Pharmaceutical compositions containing same and their use in the treatment of diseases that are associated with VEGF- and Dll4-mediated effects on angiogenesis. Nucleic acids encoding the bispecific binding molecules, host cells and methods for preparing same.