Objective: In this study, we investigated the effects of Rhizoma Cimicifugae (RC) on the induction of nitric oxide (NO) in RAW 264.7 murine macrophages treated with lipopolysaccharide (LPS). Methods: We examined whether RC have an antipyretic effect by inhibition of COX and/or NOS in fever that is evoked by an intraperitoneal injection of LPS in rats. Results: 1. RC inhibited NO metabolites produced by activated murine macrophage in a dose-dependent manner. 2. RC had an antipyretic effect in a dose-dependent manner in LPS-induced fever. 3. RC inhibited levels of both COX-2 protein and iNOS protein increased by the treatment of LPS in brain tissues as well as brain blood vessels. 4. There were no changes in proteins of nNOS/COX-1. Conclusions: RC has an antipyretic effect by attenuating the level of iNOS and COX-2 protein.