Cinnamaldehyde was shown to have significant anti-inflammatory and anti-pyretic actions in studies from both others' and our lab. Prostaglandin E2 (PGE2) plays a key role in generation of these pathological states, while PGE, synthase-1 (mPGES-1) is one of crucial biological elements in the process of PGE2 production. And as a downstream inducible terminal prostaglandin synthase of COX-2, mPGES-1 is now regarded as a more promising novel drug target than COX-2 and is attracting more and more attention from both academia and pharmaceutical industry. The purpose of present study was to further investigate the anti-inflammatory and antipyretic molecular mechanisms of cinnamaldehyde based on the mouse macrophage cell line RAW264. 7 in vitro. The PGE2 was identified by using the method of enzyme-linked immunosorbent assay (ELISA) and the expression of COX-2 and mPGES-1 at mRNA and protein levels was detected by the Real-time PCR and Western blotting methods respectively. The experimental results suggested that cinnamaldehyde could evidently reverse the increased production of PGE2induced by IL-1beta. Moreover, the up-regulated expression levels of mPGES-1 and COX-2 were significatly decreased. Together, these results provide compelling evidence that the down-regulated actions to both the production of PGE2 as well as the expression of mPGES-I might account for, at least in part, the anti-inflammatory and anti-pyretic effects of cinnamaldehyde.