Abstract: The objective of this study was to know the antibacterial compound from T.muelleri. Extraction of leaf of T. muelleri using solvents of increasing polarity, namely, n-hexane, ethyl acetate and methanol, respectively, yielded dry extracts. The extracts were tested for antibacterial activity. Ethyl acetate extract exhibited the strongest activity against standard strains of Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. The ethyl acetate extracts had been fractionated, yielded 9 fractions.The fraction EH exhibited the strongest activity against S. aureus. The separation of chemical contents of fraction EH was carried out by Sephadex LH-20 column chromatography, yielded a pure substance. The substances was identified as 3,4,5-trihidroxybenzoic acid by chromatographic and spectroscopic analysis. This substance is a well-known antibacterial activities. The activity of 1 mg 3,4,5-trihydroxybenzoic acid was equal to 0.1396 μg tetracycline HCl against S. aureus and 0.6455 μg against Methicilin-Resistant Staphylococcus aureus, also equals to 40.6035 μg penicillin G against S. aureus and equals to 2.9823 and 2.1213 μg vancomycin HCl against S. aureus and Methicilin-Resistant Staphylococcus aureus, respectively.