Methods: Using E. faecalis biofilms from clinical isolate were grown on microtiter well plate, incubated for 24 h and subjected to the following treatments: Natrium hypochlorite 2.5% (5 s), chlorhexidine 2% (5 s), natrium chloride 0.9% (5 s), and the irrigants with additional diode laser irradiation (980 nm, 15 Hz, 1.5 W, 3.5 J, 5 s). The antibacterial effects of the irrigants and diode laser were scored using colony form units (CFU). Results:The clinical isolate colony of E. faecalis that was exposed to a saline solution and diode laser application had the highest score (18700 CFU/ml), while the lowest score (80,00 CFU/ml) was recorded in the group that was exposed to a chlorhexidine 2% irrigant with additional diode laser application. Conclusion:The diode laser had an antibacterial effect on a clinical isolate of E. faecalis biofilm, and this effect was increased when it was used in addition to the application of chlorhexidine 2% and natrium hypochlorite 2.5% irrigants.