The invention relates to novel bispecific antibodies and their use in tumor therapy. The novel antibodies have the ability to bind to ErbB receptors, preferably ErbB1 receptors, which are overexpressed on many cancer tissues. Since the different specificities of the antigen-binding sites are directed to different epitopes within the binding domain of same or different ErbB receptors, these antibodies are more effective with respect to inhibition and down-regulation of the ErbB receptor and the corresponding signaling cascade.