The silver cation has broad-spectrum antibiotic activity toward Gram-positive, Gram-negative, fungal, aerobic and anerobic micro-organisms. Silver has been used to care of infected wound, pyogenic arthritis, and chronic osteomyelitis. The purpose of this study was to determine whether pure silver wire iontophoresis using milliamperage direct current has an inhibitory effect on growth in vitro of 3 different species of bacteria - Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. Using agarose based media, silver iontophoresis performed at 0, 1, 2. 4, 8 mA for 15 minutes. All experiments were performed in triplicate. Following iontophoresis, inhibition zone width of bacterial growth was measured with caliper. The inhibition of bacterial growth occured at the anodal silver electrode. Inhibition zone width of bacterial growth was significantly increased in all three bacterial species (p$lt;0.05). Between bacterial species, inhibition zone width was not significantly different. Inhibition zone and amperage showed a highly significant positive linear relationship (p$lt;0.001). The result of this study showed that pure silver wire iontophoresis with milliamperage direct current, as well as microamperage direct current, can inhibit bacterial growth in vivo.