The current study was carried out during the season of 2016 under greenhouse conditions to evaluate the efficiency of silver nanoparticles (AgNPs) as antiviral reagent to induce a systemic acquired resistance (SAR) against Tomato mosaic virus (ToMV) and Potato virus Y (PVY) and suppress their infection on tomato plants. Silver nanoparticles (AgNPs) were sprayed 7 days before inoculation with both viruses at 50, 60 and 70 ppm. The results showed that disease severity as well as relative concentration of both viruses were decreased dramatically by the treatment of AgNPs at 50 ppm compared to the other treatments. Examination the clarified sap of both viruses with TEM showed morphological evidenced that AgNPs bind to coat protein virus particles. The induction of SAR against ToMV and PVY was confirmed chemically by several parameters as indicated by increasing photosynthetic pigments, total soluble protein and the activities of peroxidase (POD) and polyphenol oxidase (PPO) compared with infected control