en Other Other Original article Original article <strong>Introduction</strong>: Silver nanoparticles are particles of silver with a size of 1 to 100 nm. These agents have various applications and particularly have received much attention for their antibacterial activity and their use in vaccine production. Among the various methods of synthesizing nanoparticles, using plants due to their high reducing capabilities and also their eco-friendliness is of interest. <strong>Methods:</strong> Silver nanoparticles (AgNPs) were synthesized using plant anise (<em>Pimpinella anisum L</em>.) and validated using UV-spectrophotometer, transmission electron microscopy and Fourier transform infrared spectroscopy. The produced AgNPs were used against <em>Escherichia coli</em>, <em>Salmonella typhimurium</em>, <em>Staphylococcus aureus</em> and <em>Enterococcus faecalis</em> to examine their antibacterial activities via agar well diffusion, disk diffusion and minimum inhibitory concentration methods. Furthermore, AgNPs were used in combination with three antibiotic disks, namely, Ceftriaxone, Tetracycline and Gentamicin to seek any cooperative effect. <strong>Results:</strong> Antibacterial effects due to the synthesized AgNPs were observed toward <em>E. coli</em>,<em> S. aureus</em>, <em>S. typhimurium</em> in this order; however, <em>E. faecalis</em> showed the highest resistance to the synthesized AgNPs. <strong>Conclusion</strong>: AgNPs synthesized using anise had similar antibacterial effects as conventional antibiotics; however with potentially less side effects. Anise, AgNPs biosynthesis, Antibacterial activity, adjuvanticity 17 24 http://vacres.pasteur.ac.ir/browse.php?a_code=A-10-111-2&slc_lang=en&sid=1 Nassir Rashnaei rashnaei.n@gmail.com 0000-0002-0488-8727 No Department of Hepatitis and AIDS, Pasteur Institute of Iran, Tehran, Iran Seyed Davar Siadat 0000-0002-6892-5603 No Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, Tehran, Iran Abbas Akhavan Sepahi 0000-0002-4112-8962 No Department of Microbiology, Faculty of Biological Sciences, Islamic Azad University TNB, Tehran, Iran Mohsen Mirzaee 0000-0003-1033-8809 No Department of Laboratory Science, Borujerd Branch, Islamic Azad University, Borujerd, Iran. Golnaz Bahramali 0000-0002-1762-4907 No Department of Hepatitis and AIDS, Pasteur Institute of Iran, Tehran, Iran Abolfazl Arab Joshaghani 0000-0002-4601-3742 Yes Department of Biology, Borujerd Branch, Islamic Azad University, Borujerd, Iran