Abstract: The antioxidant and antimicrobial activities of the extracts from peel, leaves, and bark of mangosteen (Garcinia mangostana L.), and some essential oils such as cinnamon and citrus were investigated. The antioxidant activities (IC50) of peel, leaves, and bark extracted, which were evaluated by DPPH method, were 5.94, 9.44, and 6.46 µg/ml, respectively. Either cinnamon or citrus essential oil showed no antioxidant activities with DPPH. A broth dilution method was employed to evaluate the antimicrobial activity against some Gram- positive bacteria (L. monocytogenes and S. aureus) and Gram-negative bacteria (E. coli and Salmonella sp.). The minimum inhibitory concentration (MIC) values of peel, leaves, and bark extracted against Gram-positive bacteria were ranged from 0.025-0.78 mg/ml. While the minimum bactericidal concentration (MBC) values were between 0.05-0.39 mg/ml. MIC and MBC values of cinnamon against S. aureus, E. coli and Salmonella sp. were 3.13 and 6.25 mg/ml, respectively. Citrus oil showed effect on only S. aureus with MIC and MBC values of 6.25 and 12.50 mg/ml, respectively.