Polyalthia stenopetala essential oils were extracted by hydrodistillation from the leaves and were analyzed using gas chromatography-flame ionization detector (GC-FID) and gas chromatography/mass spectrometry (GC/MS) system. Thirty one compounds were identified from the analysis. The most abundant components in the leaves oil are curzerene (37.56%) followed by viridiflorol (11.59%), germacrene B (3.77%) and aromadendrene (4.01%). The antimicrobial activity of the oil essential oils was determined with disk diffusion method and minimum inhibitory concentration (MIC) assay. Four bacteria, Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 25922) Psedomonas aeruginosa (ATCC 10145) and two yeasts, Candida albicans (ATCC 10231) and Saccharomyces cerevisiae (ATCC 4098) were selected. The crude oil shows the most reactivity against B. subtilis (ATCC 6633) and C. albicans (ATCC 10231) with an inhibitory zone of 11mm. The minimum inhibitory concentration (MIC) of sample against Staphylococcus aureus (ATCC 25923), Bacillus subtilis (ATCC 6633), Escherichia coli (ATCC 25922) Psedomonas aeruginosa (ATCC 10145) and Candida albicans (ATCC 10231) in range of 0.5 mg/ml – 1.0 mg/ml which can categorized as strong.