Fimbristylis ovata (Burm.f.) Kern has long been used in traditional medicine for the treatment of inflammationassociated diseases. However, there has been no scientific data on the active components or the biochemical or molecular mechanism responsible for these therapeutic effects. The aim of this study was to investigate the antioxidant activity of F.ovata and the effect of its extract on the regulation of RAGE gene in human lung adenocarcinoma epithelial cell line (A549). We investigated total phenolic content by Folin-Ciocalteu’s phenol assay and evaluated antioxidant activity by DPPH assay and ABTS assay. The effect of F. ovata ethanol extract on cell viability and RAGE gene expression were evaluated on A549 cells by MTT assay and RT-PCR respectively. Total phenolic content of F. ovata extracted by water and ethanol were 161.0 ± 15.2 and 777.7 ± 45.4 μg GAE/g dried F.ovata respectively. Antioxidant capacity of the water and ethanol extract were 34.0 ± 4.4 μg and 970.0 ± 64.7 μg VCEAC/g dried F. ovata respectively. Antioxidant capacity of F. ovata extracted by water and ethanol were 481.1 ± 98.1 and 6,717.0 ± 182.5 μg TEAC/g dried F. ovata respectively. Upon incubation with the ethanol extract at concentration up to 100 μg/ml, cell viability was more than 80%. Interestingly, the ethanol extract could significantly inhibit RAGE gene expression in human lung adenocarcinoma epithelial cell line.