Background : This study aimed to investigate the antioxidant and anti-inflammatory activities of water chestnut (Trapa japonica Flerow) extract. Methods and Results : The antioxidant and anti-inflammatory activities of 100% methanol extract of water chestnut were investigated. The methanol extract was evaluated for its total phenolic and flavonoid content, DPPH•(1,1-diphenyl-2-picrylhydrazyl) free-radical scavenging activity,reducing power, andeffect on nitric oxide (NO) production and cell viability using real-time polymerase chain reaction (qPCR). The total phenolic content was 438.31 ㎍ allic acid equivalent (GAE)/㎎ extract and the total flavonoid content was 61.40 ㎍ quercetin equivalent (QE)/㎎ extract. In addition, results revealed the extract possessed antioxidant activity (DPPH• free-radical scavenging activity) with IC50 value of 5.28 ㎍㎖ The reducing power of the extract was assayed spectro photometrically and showed Abs of 0.71 at 100 ㎍㎖ Furthermore, extracts of water chestnut exhibited no cytotoxicity in RAW 264.7 cells. In addition, the NO assay revealed that LPS-induced NO production was significantly inhibited following treatment with water chestnut extracts. The expression of pro-inflammatory proteins such as inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 decreased in a concentration-dependent manner. The water chestnut extract also decreased tumor necrosis factor α (TNF-α) release. Conclusion : Therefore, the present findings provide scientific evidence for the nutritional potential, chemical composition, and biological activities of Trapa japonica Flerow anddemonstrate its potential use as a functional food forapplication in the pharmaceutical industry