The present invention relates to T cell receptors (TCRs) that bind the HLA-A*02 restricted peptide GVYDGREHTV (SEQ ID NO : 1) derived from the germline cancer antigen MAGE A4. Said TCRs may comprise non-natural mutations within the alpha and/or beta variable domains relative to a native MAGE A4 TCR. The TCRs of the invention are particularly suitable for use as novel immunotherapeutic reagents for the treatment of malignant disease.