The aim of the present study was to examine the anti-inflammatory activities of extracts from Tetraselmis suecica with respect to nitric oxide (NO) production, tumor necrosis factor (TNF)-${alpha}$ and interlukin (IL)-6 release in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. We prepared methanolic extracts and water extract using protease. Of all the prepared extracts, 80% methanol extract exhibited the strongest anti-inflammatory effect. Thus, we further characterized the hexane fraction (He-TS) and ethyl acetate fraction (EA-TS) that contained potential bioactive compounds from the 80M-TS fraction of T. suecica. Both He-TS and EA-TS fractions resulted in a significant and dose-dependent inhibition of LPS-induced NO production, TNF-${alpha}$, and IL-6 release (p<0.05). This strong inhibition of various inflammatory mediators such as NO, TNF-${alpha}$, and IL-6 by EA-TS fraction from T. suecica suggests that this fraction might contain a potential bioactive compound that would be a good candidate for the development therapeutic anti inflammatory agent.