Objective: Black-pigmented bacteria represent one of the most prominent causes of chronic periodontitis. The objective of this study is to investigate the in vitro antibacterial effect of an infusion of binahong leaves (Anredera cordifolia (Ten.) Steenis) against black-pigmented bacteria. Methods:The black-pigmented bacteria were isolated from the periodontal pocket of a patient with chronic periodontitis. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by means of a dilution test using 10 5 cfu/ml of bacteria cultured on Brucella broth containing blood and kanamycin, which was exposed to a 20%, 30%, 40%, 50%, 65%, 80%, and 95% infusion of binahong leaves and then incubated for 24, 48, and 72 h. In the blank disc diffusion test, a 50%, 65%, 80%, 95%, and 100% infusion was dripped onto a paper disc placed at the center of a Brucella agar bacterial culture and then incubated for 24 h. Results:The MIC and MBC of the binahong leaf infusion were >65% and 80%, respectively, while the antibacterial activity was not correlated with the duration of the exposure to the infusion. The diffusion test showed that an increased concentration of the infusion resulted in an increased diameter of the inhibition zone that ranged from 0.42 mm (50% infusion) to 1.42 mm (100% infusion). Conclusion:Binahong leaves infusion has potential efficacy against black-pigmented bacteria.