Bacterial infections are a costly sequela in any wound. The corrosion properties of 0.15, 0.30, 0.45 and 0.60 g of Mg metal were determined in Mueller-Hinton broth by serially measuring the Mg2+ concentrations and pH over 72 h. In addition, the effect of Mg metal, increased Mg2+ concentration and alkaline pH on the in vitro growth of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus were evaluated in three separate experiments. The primary outcome measure for culture studies was colony-forming units/ml compared to appropriate positive and/or negative controls. Regardless of the mass of Mg added, there was a predictable increase in pH and Mg2+ concentration. The addition of Mg and an increase of pH resulted in antibacterial effects similar to the fluoroquinolone antibiotic; however, a simple increase in Mg2+ concentration alone had no effect. The results demonstrate an antibacterial effect of Mg on three common aerobic bacterial organisms, the mechanism of which appears to be an alkaline pH.