A method of co-expressing a portion of the VSV G protein gene or a truncated “stem” portion with GP64 and a retrovirus increases the titer of retroviral vectors. A truncated VSV G protein, preferably comprised of a small segment from the C-terminal portion of the ectodomain plus the transmembrane (TM) and cytoplasmic tail (CTD) domains of VSV G, co-expressed with retroviral vectors, enhances the production titers of the retroviral vectors. A preferred embodiment uses a VSV G construct that includes an N-terminal c-Myc epitope plus 42 amino acids from the C-terminal portion of the ectodomain, 20 amino acids from the predicted TM domain, and 29 amino acids from the predicted CTD of the VSV G protein.