Objective: To investigate the antipyretic effect of the flavonoids from Trollius ledebouri Reichb (FTLR) on ferile rabbits induced by endotoxin and its mechanism. Method: The effects of the essential oil of Ligusticum chuanxiong Hor t. on changes of body temper ature and hypothalamic content of monoamine nerval transmitter were measured in the rabbits following intravenous injection of bacterial endotoxin(ET) The febre rabbits model was established by ear intravenous injection endotoxin of 250 ng·kg-1 of body weight

and then the rabbits that the body temperature rises 1 ℃ were divided into groups randomly:FTLR 200 mg·kg-1 group

100 mg·kg-1group and 50 mg·kg-1 group

Asprin 100 mg·kg-1 group (positive control)

and fever model control group

at the same time. All groups were intragastric given the same volume drugs or distilled water. After treatment measured temperature 1 time each hour and that kept on four hours. The levels of TNF-α and IL-1β in serum and PGE2 in cerebrospinal fluid were measured by ELISAE assay. Result: At each time point

the average body temperature of rabbits in FTLR 200

100 mg·kg-1 and asprin 100 mg·kg-1 groups were lower than that of the model control group(P<0.01)

in FTLR 50 mg·kg-1group the average body temperature of rabbits were lower than that of the model control group after treatment 2-4 hours. The expression level of TNF-α and IL-β in serum and PGE2 in cerebrospinal fluid were significantly lower than that of model group (P<0.05 or P<0.01). Conclusion: FTLR has significantly antipyretic effect on ET-induced febris response in rabbits and in a dose-dependent manner..Its mechanism may be related to inhibition expression of TNF-α and IL-1β in serum and PGE2 in cerebrospinal fluid.