The present invention relates to a HER2-specific binding molecule that specifically binds to two different epitopes of HER2 comprising: (a) a first binding (poly)peptide that specifically binds to a first epitope of HER2 and (b) a second binding (poly)peptide that specifically binds to a second epitope of HER2. The present invention further relates to a nucleic acid molecule encoding the HER2-specific binding molecule of the invention, a vector comprising said nucleic acid molecule as well as a host cell or a non-human host transformed with said vector. The invention also relates to a method of producing a HER2-specific binding molecule of the invention as well as to pharmaceutical and diagnostic compositions. Moreover, the present invention also relates to the HER2-specific binding molecule, the nucleic acid molecule, the vector or the host cell of the invention for use in the treatment of tumors.
