Objectives: To investigate the antibacterial activity and the sealing ability of six contemporaryantibacterial bonding agents at the resin-teeth interface at three time intervals namely three weeks,three months and six months. The six bonding agents used in this study were: AdheSE One,Clearfil SE, AdheSE One F, Clearfil protect bond and Adper Prompt L-Pop and Syntac.Materials and Methods: 60 samples were prepared for the agar diffusion test. 20 μl of eachbonding agent were applied on a sterile paper discs, light cured, placed on a plate inoculated witheach bacterial suspension and incubated anaerobically for 48 hours at 37ºC. The diameters of theinhibition zones formed around the discs were measured and recorded. 300 teeth were used for theantibacterial invasion and the microleakage tests. For the Bacterial invasion test, standardizedcavities were prepared in the middle third of the buccal surfaces of the extracted premolars. Thesix bonding agents were applied, cured and then restored with light-cured resin composite. Teethwere covered by a nail varnish except on the restoration and 1 mm around it. Every tooth wasimmersed in a medium of brain heart infusion broth and 1% sucrose. The medium was inoculatedwith either type of bacteria for three weeks, three months and six months at 37ºC. The resincomposite was removed from the cavity after each interval and the number of remaining bacteriain each cavity was counted. To evaluate the sealing ability, the dye penetration along the toothrestorationinterface was examined using a stereomicroscope, before and after the three immersionperiods. For the ultramorphological assessment of the dentin-resin interface, one sample out offive samples was taken of the microleakage test, to be examined under the EnvironmentalScanning Electron Microscope. Data were recorded, tabulated and statistically analyzed.Results: For the agar diffusion test, all the tested adhesives showed different degrees ofantibacterial activity except AdheSE one which showed no inhibition zone. Clearfil Protect Bondshowed the highest inhibition zone. In the tooth model test, all the tested adhesives, showedsignificantly different bacterial counts among each other for all the test period intervals. All typesof adhesives showed significantly higher antibacterial effect against streptococci than lactobacilli.The mean counts of both types of bacteria significantly increased by time for all tested adhesives.For microleakage tests, all the adhesives showed different degrees of microleakage. AdheSE OneF adhesive showed the least significant percentage of microleakage, while CLearfil Protect bondand Clearfil SE adhesives showed the highest significant percentages of microleakage after sixmonths of bacterial immersion. The microleakage for all the tested adhesives significantlyincreased by time. Ultramorphological examination by ESEM confirmed the results of theinvestigation tests.Conclusions: This study concluded that the tested adhesives have different antibacterial activityagainst cariogenic bacteria. The incorporation of antibacterial ingredients to the adhesive systemsseems to be unreliable procedure to provide adequate antibacterial activity at the resin-toothinterface. Improper sealing ability of the tested adhesives at the resin-tooth interface constitutes amajor failure to restoratives durability.