The mangosteen (Garcinia mangostana Linn) fruit is dubbed the "queen of fruits" because of its fragrant aroma, sweet taste and slightly sour but rich in health benefits. This research aims to determine the antibacterial potential of mangosteen pericarp to inhibit the growth of E. coli ATCC 25922 and S. Aureus ATCC 25923. Mangosteen pericarp were extracted using maceration method and antibacterial sensitivity testing by Kirby Bauer diffusion method that was duplicated four times. The result of this study is that mangosteen pericarp extract showed inhibition against Staphylococcus aureus ATCC 25923 with diameter zone of inhibition of 10.23 mm, 10.95 mm, 13.45 mm, 16 mm, 19.5 mm on 10%, 30%, 50%, 70% and 100% of extract mangosteen pericarp respectively and there is no zone of inhibition on mangosteen pericarp extract against Escherichia coli ATCC 25922. This research needs to be done with a better methodology and technique