To fine out the anti-inflammatory activities of the C. fragile. and its mechanism were investigated in macrophages induced by Peptidoglycan (PGN). Treatments of macrophages with 100 ug/ml of ethanol extract of Codium fragile (EECF) inhibited PGN-induced IL-6, NO and PGE2 production in a dose-dependent manner as well as expression of iNOS and COX-2. EECF inhibited PGN-induced extracellular signal-regulated kinase (ERK) 1/2, JNK 1/2 and p38 MAPK phosphorylation, which suggests that EECF inhibits IL-6 and NO secretion by blocking MAPKs phosphorylation. These findings may help elucidate the mechanism by which EECF modulates RAW 264.7 cell activation under inflammatory conditions.