To observe the antipyretic effect of Reduning injection (RDN) on lipopolysaccharide (LPS)-induced fever rats and its impact on centric fever medium. Rats were randomly divided into the blank control group, the model group, the Metamizole group, and high and low-dose RDN groups. Except for the blank control group, all of the rats were injected intraperitoneally with LPS (80 microg x kg(-1)) to observe their body temperature changes. The double-antibody sandwich ELSIA method was adopted to determine cAMP content in hypothalamus and MPO in lung tissues of fever peak rats. The high-dose RDN group can obviously reduce the temperature rise in fever rats, and cAMP and MPO content in hypothalamus. RDN showed significant antipyretic effect, which may be related with the reduction of cAMP content in hypothalamus and MPO in lung tissues.