Abstract: The changes of arginine vasopressin （AVP） contents in the plasma, cerebrospinal fluid （CSF）,septal area and hypothalamus of rabbits during endotoxin fever were observed. At the 90 th minute after treatment with endotoxin （10 ng/kg,iv） the temperatures of the treated rabbits rised 1.00±0.36℃（n = 9）,the A VP contents decreased markedly in plasma and CSF,increased markedly in hypothalamus and remained unchanged in septal area of the febrile rabbits as compared with the control animals.The results suggested that endotoxin fever might promote the synthesis and release of AVP in hypothalamus of rabbit.