A needle-free transdermal injection device was evaluated for effectiveness of vaccine delivery and for injection site lesions. A total of 96 pigs were vaccinated for pseudorabies virus (PRV) and Mycoplasma hyopneumoniae (M.hyo.). Pigs were divided into three groups; the first group served as unvaccinated controls, the second group was vaccinated with conventional hypodermic needles, and a third group was vaccinated with a needle-free, air-powered injection device. Pigs were tattooed on the neck to mark the injection sites. Blood samples were collected from the pigs at 11−13 days and 23−25 days after injection, and the serological response was measured. Injection sites were collected at slaughter and dissected to evaluate tissue damage. The results showed that both injection methods produced similar serological responses in the vaccinated pigs and both were significantly greater than the unvaccinated controls. The injection site examinations have shown no lesions in any of the pigs. The results show the needle-free, transdermal injection device to be effective and safe. Elimination of needles will prevent residual needle fragments in carcasses and associated carcass defects from injection site lesions