The antimicrobial use of silver has had a remarkable history, beginning with the use of silver nitrate by the Romans as a medicinal agent and extending to the present time, where silver is employed in a wide range of antimicrobial consumer products and wound care dressings. While the efficacy of silver ion as an antimicrobial agent has been firmly established, little reliable data concerning its minimum inhibitory concentration (MIC) has been collected. In this study, we demonstrate the use of modified Szybalski density gradient plates coupled with silver analysis by Graphite Furnace Atomic Absorption Spectrometry to determine quantitatively the MIC of silver ion for Escherichia coli, Pseudomonas aeruginosa, Methicillan-Resistant Staphylococcus aureus, Staphylococcus epidermidis, and Actinobacter baumannii.