The tobacco vein mottling virus (TVMV) and alfalfa mosaic virus (AMV) coat protein (CP) genes were engineered into three commercial Burley tobacco genotypes to allow us to study the efficacy and properties of viral coat protein mediated resistance (CPMR). Over 200 transgenic lines were generated and screened in the greenhouse. Fifty TVMV-CP and thirty AMV-CP transgenic lines were evaluated in the field for response to mechanical inoculation with TVMV, tobacco etch virus (TEV), potato virus Y (PVY), and AMV, respectively. Hybrids combining two CP genes were also generated and evaluated under field conditions. The results suggested that the combination of the two strategies, CPMR coupled with an endogenous virus resistance gene significantly extended the range and magnitude of virus resistance and provided a valuable new source of protection against virus infection. Combining two CP genes by hybridization of transgenic lines appeared to be an effective means of achieving a wider range of virus resistance. Our results have important implications for programs using CPMR to improve virus resistance in crops. We have shown the importance of selecting an appropriate recipient genotype; and, we have provided guidelines for the development of transgenic lines with high virus resistance. We concluded that a relatively large number (30-50) of primary transformants are needed in order to obtain optimum resistance. We also found that field evaluation of transgenic lines is essential. It is not possible to predict field resistance based on greenhouse evaluations alone.