A. calamus that grows in province of Baluchistan and Kerman in Iran plays a major role in the revival of traditional medicine. Despite the useful role of this plant in many ailments, its anti-bacterial properties are not well understood. In this study, we investigated anti-bacterial activities of rhizomes ware of A. calamus against various strains of bacteria such as Staphylococcus aureus and Escherichia coli. The anti-microbial activity of extracts of A.calamus was assessed by disc diffusion method. Rhizomes extracted by ethanol, methanol solvents and essential oil were obtained by clevenger apparatus. Antibacterial effects of the extracts tested at concentrations (25, 100, 200, 250, 300, 400 mg/ml). The Minimal Inhibitory Concentration (MIC) of extracts ranged from 25-100 mg/ml against the susceptible bacteria. All the Minimal Bactericidal Concentrations (MBCs) were the same as the MICs. Our results revealed that ethanolic and methanolic extracts have an inhibitory effect on all gram positive and negative strains and it is comparable with kanamycin, an anti-bacterial reference drug. Amongst extracts of A.calamus, ethanolic extracts showed maximum inhibitory activity (16mm) against Staphylococcus epidermidis. So we can conclude that this plant has anti-bacterial properties on all gram positive and negative bacteria. The result can be related to the nature of the compounds found in this plant. The effective GC-MS method was performed for the determination of essential oil compounds of A.calamus. The Gas Chromatography and Mass Spectrometry (GC-MS) analysis revealed that the presence of phenyl propanoids, monoterpenes, sesquiterpenes and β-asarone in essential oil of the plant caused its antibacterial properties. Our result showed that the ethanolic and methanolic extracts of A. calamus could be useful for the development of effective treatment for the control of infectious diseases.