The present invention provides new, fully human EphA4 monoclonal antibodies with distinct binding characteristics. Also disclosed are antigen binding fragments of these antibodies, bispecific forms of these antibodies, and conjugates of these antibodies. In addition, nucleic acids encoding these antibodies, antigen binding fragments, bispecific antibodies and conjugates are disclosed. These monoclonal antibodies, antigen binding fragments, bispecific antibodies, conjugates, nucleic acids and vectors are of use for identifying and treating a subject with a disease or condition involving abnormal EphA4-mediated signaling.