In this study, the effects of nisin and clove essential oil on shelf life of beef were investigated in order to evaluate their antimicrobial activities. It was determined that clove essential oil has a wide spectrum on Gram (+) and Gram (-‐) bacteria. While L. monocytogenes was the most resistant bacteria among the Gram (+) bacteria, B. thermosphacta was found to be the most sensitive bacteria. Out of Gram (-‐) bacteria, Y. enterocolitica was the most sensitive bacteria and P. aeruginosa was the most resistant one. The antimicrobial activities of clove essential oil and nisin on beef were tested both separately and in combination. Although clove essential oil was successful in vitro, its activity on prolonging shelf life of beef was found to be limited (4 days). Clove essential oil alone was more effective on the shelf life than that of combinations and nisin alone. The increase in concentrations indicates an antagonistic interaction between clove essential oil and nisin. Key words: Antibacterial effect, Beef, Clove essential oil, Nisin, Syzygium aromaticum. Sığır Eti Raf Ömrü Üzerine Karanfil Uçucu Yağı ve Nisinin Etkisi