BACKGROUND Pyrrosia petiolosa is commonly used as a traditional Chinese medicine for treatment of acute pyelonephritis, chronic bronchitis and bronchial asthma. This study aims to evaluate the antibacterial activity of the ethanol extract and its derived fractions of Pyrrosia petiolosa obtained with solvents of different polarities and to perform the anti-inflammatory screening. METHODS The powdered aerial parts of Pyrrosia petiolosa were used to extract various fractions with ethanol, petroleum ether, ethyl acetate, N-butanol and aqueous. Qualitative phytochemical screening was performed on the ethanol extract, petroleum ether fraction, ethyl acetate fraction, N-butanol fraction and aqueous fraction. The agar diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were employed to evaluate antibacterial activity of the ethanol extract and fractions. The in vitro cytotoxicity of ethanol extract and fractions was determined using MTT assay. The anti-inflammatory activity was analyzed using the mouse ear swelling induced by xylene. RESULTS The phytochemical screening revealed the presence of anthraquinones, flavonoids, terpenoids, steroids, saponins, phenols and reducing sugars in the extract and fractions. Antibacterial results showed that petroleum ether fraction and N-butanol fraction inhibited all the tested microorganisms with the maximum inhibition zone of 15.25±0.35 mm. Ethyl acetate fraction also exhibited good antibacterial activity except Pseudomonas aeruginosa ATCC 27853, while extract and aqueous fraction inhibited 8 out of 13 (61.5%) of the tested microorganisms. The MIC values of ethanol extract and fractions ranged from 1.25 to 10.00 mg/mL and most of the MBC values were equal or twice as high as the corresponding MIC values. The in vitro cytotoxicity showed the ethanol extract and fractions exhibited non-toxic or low toxic activity against lung cancer cell lines A549 and mouse spleen cells. In anti-inflammatory experiment, ethanol extract at 5.0 and 10.0 mg/kg exhibited significant anti-inflammatory activity against the mouse ear swelling induced by xylene and the maximum inhibition rate reached as high as 67%. CONCLUSIONS Pyrrosia petiolosa could be a potential candidate for future development of a novel antibacterial and anti-inflammatory agent.