It is well known that Silver nanoparticles has great affinity against many pathogenic microbes i.e silver nanoparticles possess good antimicrobial properties against many bacteria and fungi. Staphylococcus aureus is one of the most pathogenic bacteria causing infections on skin, respiratory tract, not only this it also cause life threatening diseases such as pneumonia, meningitis etc. Inhibitory effect of silver nanoparticles against staphylococcus aureus gram positive bacteria was evaluated by in-vitro disc diffusion method.The bacterial strains were treated with silver nanoparticle discs at varying concentrations. The antibacterial activity was evaluated by measuring zone of inhibition around antimicrobial disc.