Abstract: The inhibition efficiency of antimicrobial drug toward the corrosion behavior of mild steel using aqueous environment was studied using weight loss method and A.C. Impedence techniques. The obtained result revealed that the drug performed well as corrosion inhibitor in aqueous environment. The inhibition efficiency increased with increasing inhibitor concentration. The highest inhibition occurs through adsorption of the Inhibitor molecule on the metal surface without modifying the mechanism of corrosion process. The adsorption parameters were also used to evaluate the inhibitive property of drug. It was also found that the corrosion inhibition behaviour of tetracycline drug is more in sodium chloride.