<p>Aim: The aim of this study is to improve the antibacterial properties and investigate the physical properties of modified dental luting cements (polycarboxylate cement, glass ionomer cement, dual-cure cement, composite resin cement) with oleuropein addition.Materials and Methods: The dental luting cements were modified by adding Oleuropein 1% by weight. Unmodified luting cements were referred as the control group. In order to determine the antibacterial effect of each group Modified Direct Contact Test method and E. faecalis was used. The microhardness values of all samples was measured with Vickers microhardness tester. All samples were evaluated by Scanning Electron Microscopy (SEM). Results: Fewer bacterial colonies were detected in the media of the experimental group compared to the control group. While the Vickers microhardness values of polymer-containing cements decreased with the addition of oleuropein, no statistical difference was found in polycarboxylate and glass ionomer cement. Conclusion: According to the results of this study, the addition of oleuropein improved the antibacterial properties of the luting cements but physical properties of resin based cements are negatively affected. The results obtained may shed light on the studies to be carried out on the development of luting cements.Key Words: Antibacterial, luting cements, oleuropein<br></p>