Potato virus X (PVX) and potato virus Y (PVY) infection in potato may result in the loss of certification of seed potatoes and affect quality and yield of potatoes in commercial production.  We transformed a major commercial cultivar of potato, Russet Burbank, with the coat protein genes of PVX and PVY.  Transgenic plants that expressed both CP genes were resistant to infection by PVX and PVY by mechanical inoculation.  One line was also resistant when PVY was inoculated with viruliferous green peach aphids.  These experiments demonstrate that CP protection is effective against mixed infection by two different viruses and against mechanical and aphid transmission of PVY.