The ancient-Iranians were familiar with many medicinal herbs and were aware of their usefulness in treatment of various diseases. In this study Thymus vulgaris L., Ziziphora tenuior L. and Mentha Spicata L. extracted with methanol 96°and the antimicrobial effects of extracts were evaluated on Escherichia coli PTCC 1330 and Staphylococcus aureus PTCC 1337 by “using the method of Collins” and “disk agar diffusion method”. The results show that methanolic extracts were quite effective in 2000 μg/ml concentration on Escherichia coli PTCC 1330 and Staphylococcus aureus PTCC 1337 and were prevented from growth them on medium. In “disk agar diffusion method”, 10, 20, 30 and 40 % methanolic extract concentrations, was deterrented effect on Escherichia coli PTCC 1330 and Staphylococcus aureus PTCC 1337. The Thymus vulgaris L., Ziziphora tenuior L. and Mentha Spicata L. extracts presented the more effective impact on the growth of Staphylococcus aureus PTCC 1337than Escherichia coli PTCC 1330 (p<0.05). Among the bacteria tested, E. coli was the resistant bacterium against Thymus vulgaris L., Ziziphora tenuior L. and Mentha Spicata L. extracts E. coli is known to possess a high level of intrinsic resistance to most of the antimicrobial agents due to a very restrictive outer membrane barrier. As a result alcoholic extracts of Thymus vulgaris L., Ziziphora tenuior L. and Mentha Spicata L., have been strong antimicrobial activity against many food pathogen bacteria. Results showed Thymus vulgaris L., Ziziphora tenuior L. and Mentha Spicata L. extracts can be used as natural antimicrobial in food products.

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