Retrovirus-mediated gene transfer is currently the method of choice for the transfection of human T lymphocytes for applications in gene therapy. Use of retroviral vectors, however, is hampered by limits on the size of the genetic material to be transferred, the requirement of dividing target cells, and by potential safety questions. Synthetic peptide-enhanced or adenovirus-enhanced receptor-mediated transferrinfection of DNA (SPET and AVET, respectively) is a powerful method for the introduction of genetic material into mammalian cells. Although transferrin has proven to be a useful ligand for gene transfer in many cell types, gene expression in T cells with transferrin/DNA complexes is usually not satisfactory. To improve gene transfer to T cells, antibodies directed against the CD3-T cell receptor complex were tested for their ability to function as ligands for DNA delivery. In T cell lines, up to 50% of the cells expressed a beta-galactosidase reporter gene using anti-CD3 gene transfer complexes. Applying optimized conditions, prestimulated primary peripheral blood lymphocytes were also transfected successfully, although at a lesser efficiency (5%).