Danggui-Shaoyao-San, a famous traditional Chinese prescription, has been widely used in China for treating various gynecological inflammatory diseases including dysmenorrhea, but it is still poorly understood how it works on those inflammatory disorders. Prostaglandin F(2alpha) (PGF(2alpha)), one important mediators of inflammation, plays crucial roles in the pathological mechanism responsible for dysmenorrhea. Here, we demonstrate that Danggui-Shaoyao-San significantly suppresses oxytocin-evoked PGF(2alpha) production of rat endometrial epithelial cells in a concentration-dependent manner. Furthermore, Danggui-Shaoyao-San-mediated down-regulation of cyclooxygenases-2 message RNA transcription, protein expression and enzyme activity in endometrial epithelial cells may be involved in the inhibitory effect on PGF(2alpha) production. Our study provides a possible mechanism for the bioactivity of Danggui-Shaoyao-San for treating dysmenorrhea and other gynecological disorders.