Overproduction of prostaglandins has been considered in mediation of inflammation and carcinogenic process. On this line, the inhibitors of prostaglandin biosynthetic enzyme cyclooxygenase (COX) have played a role of anti-inflammatory and cancer chemopreventive agents. In our continuous efforts to search anti-inflammatory and chemopreventive agents from natural products, bioassay-guided fractionation led to the isolation of curdione from the rhizome of Curcuma zedoaria with the inhibitory effect on the production of prostaglandin $E_2$ in lipopolysaccharide (LPS)-stimulated mouse macrophage RAW 264.7 cells in a concentrationdependent manner ($IC_{50}=1.1{mu}M$). Mechanistic studies suggest that the suppression of cyclooxygenase-2 (COX-2) mRNA expression is, at least in part, involved in this inhibitory activity of curdione.