The Ag(I) ion has well established antibacterial and antifungal properties. Exposure of Staphylococcus aureus to MIC80 AgNO3 (3 lg/ml) lead to an increase in the activity of superoxide dismutase, glutathione reductase and catalase at 30 min but activity declined by 60 min. In addition, exposure of cells to this metal ion for 1 h lead to increased expression of a number of proteins such as elongation factors Ts, Tu and G, fructose-bisphosphate aldolase and triosephosphate isomerase but their expression declined following 4 h exposure. ATP binding cassette transporter protein and oligoendopeptidase F showed increased expression at 4 h. While Ag(I) is a potent antimicrobial agent this work demonstrates that S. aureus can mount a short-term protective response to exposure to the metal ion but that this is eventually overcome.