Expression of native transgenic T cell receptors in recipient human T cells is often insufficient to achieve highly reactive T cell bulks. Here we show that codon modification of an HPV16E7-specific T cell receptor (TCR), together with omission of mRNA instability motifs and (cryptic) splice sites, leads to a dramatic increase in the expression levels of the transgenic TCRs in human CD8+ T cells. The codon-modified TCRs have been tested in three different configurations in the retroviral vector LZRS: (1) TCRalpha-IRES-GFP in combination with TCRbeta-IRES-NGFR, (2) TCRalpha-IRES-TCRbeta, and (3) TCRalpha-2A-TCRbeta. T cells carrying the codon-modified TCRs are functionally active against target cells loaded with relevant peptide, model tumor cells expressing the specific epitope as well as cervical carcinoma cells. The significant improvements we report here in the functional expression of specific human TCRs will hopefully expedite clinical application of TCR transfer-based immunotherapy.