Objectives: To determine the in vitro anti-inflammatory activity of solvent extract of the marine microalgae, Nannochloropsis sp. Materials and methods: The preliminary assays for antiinflammatory activity such as protein denaturation inhibition and membrane stabilization were evaluated in the various solvent extracts (petroleum ether, aqueous, isopropanol, methanol, ethyl acetate) of the microalgae, Nannochloropsis sp. and in vitro antiinflammatory effect was determined in ethyl acetate extract against murine macrophage (RAW 264.7) cells. The compounds present in the extract were analyzed through GCMS. Results: The ethyl acetate extract exhibited good protection against protein denaturation at an inhibition rate of 72.66 ± 0.46% and provides significant membrane stabilization by inhibiting hemolysis by 92.02 ± 0.10 %. The in vitro anti-inflammatory activity was found to be dose dependent by inhibiting the inflammatory mediators such as COX (62.08 ± 0.035%), LOX (65.84 ± 0.19%) and also reduced production of the MPO (0.000797 ± 0.00003 IU/ml) and iNOS (90.44 ± 0.19%) thereby cellular nitrite level to 342.54 ± 0.49 µg/ml. The GCMS analysis for bioactive compounds showed a total of 16 compounds in which phenols and lipids are the major components. Application: The result suggests that the microalgae contain potential antiinflammatory compounds which can be explored in therapeutics against inflammation induced diseases.