P Periodontitis is a periodontal disease caused by the presence of bacterial colonies in plaque. One of the bacteria that causes periodontitis is Treponema denticola. Treponema denticola is an anaerobic Gram-negative bacteria and spirochetes belongs to the 'red complex'.. Mangosteen is a tropical fruit found in Indonesia. The mangosteen fruit, especially the rind, has flavonoids, xanthones, tannins, terpenoids, and saponins compounds that have high antibacterial. In a study conducted by Komansila et al., Extracts from Therefore, the aim of this study is to determine the effectiveness of mangosteen rind extract on the growth of Treponema denticola bacteria. Mangosteen rind extract and controls were added to petri dishes which were inoculated with Treponema denticola and then incubated for 1x24 hours, followed by measurement of the minimum inhibitory concentration (MIC) determined from the clear zone formed. Each mangosteen rind extract concentration has a diameter inhibition zone with an average of: 50% concentration of 12.53 mm, 25% concentration of 6.97 mm, 12.5% concentration of 6.27 mm, concentration of 6.25 % of 4.27 mm while the concentration of 3.125% is 2.73 mm. The result shows that mangosteen rind extract has an antibacterial effect on Treponema denticola. The higher the concentration used, the greater the inhibitory zone formed.