Silver-containing oxide coatings on AZ31 Mg alloys were fabricated by microarc oxidation (MAO) in AgNO3-containing sodium silicate (Na2SiO3)-based electrolyte, and their physical and chemical properties were investigated, particularly focusing on corrosion resistance and antibacterial activity. The porous oxide coatings consisting of Mg2SiO4 and MgO formed in both AgNO3-containing and AgNO3-free electrolytes and the MAO coatings were composed of a porous outer layer and a dense inner layer. MAO in AgNO3-containing electrolyte resulted in a thicker oxide coating, especially a thicker fluorine (F)-rich inner layer. Fluorine (F) was rich in the dense inner layer, and Ag was preferentially located close to the coating surface. The potentiodynamic test indicated that Ag-containing MAO coating had a more positive corrosion potential (-1.42 V), lower corrosion current density (0.02 mu A/cm(2)), and thus higher corrosion resistance (1824 k cm(2)) compared to Ag-free MAO coatings (-1.53 V, 0.32 mu A/cm(2), and 131 k cm(2), respectively). The electrochemical impedance spectroscopy results revealed that the higher corrosion resistance of Ag-containing MAO coating was due to an order of magnitude higher resistance of the dense inner layer. Ag-containing MAO coating showed an excellent antibacterial activity over 99.9% against two strains of bacteria, Staphylococcus aureus and Escherichia coli.