This chapter considers the experimental transmission of virus without the aid of natural vectors. The ability to be transmitted between plants is a fundamental property of plant viruses that is necessary for their survival and spread. For woody plants in particular, graft inoculation to sensitivie indicators is the only way of identifying some viruses and some virus strains, and remains a widely used technique for transmission and diagnosis. For diagnostic purposes, the advent of serological and molecular techniques for rapidly identifying infection with specific viruses has tended towards a decrease in the use of transmission studies. Graft-inoculation was the first widely used technique for the transmission and detection of viruses, especially of woody plants. The speed of movement of virus across the graft junction can vary enormously depending on the virus, the plant partners involved, the grafting technique used, and the time of year when grafting takes place.