This study was designed to systematically investigate expression of TNF α,IL-1β,I1-6 mRNA in the liver,lungs and kidneys, release of TNF α in the above tissues,their relationship with hepatic, pulmonary and renal dysfunction,and distribution of endogenous endotoxin in tissues after hemorrhagic shock in mice and rats, with reverse-transcription-polymerase chain reaction, ELISA, etc, to elucidate the kinetics of expression and release of major cytokines in vital organs,their role and mechanism of production in shock. The results were: ①expression of TNF α, IL-1 β, IL-6 mRNA in vital organs successively increased after hemorrhagic shock and resuscitation,and TNF α expression was the first to appear followed by IL-1β. Though expression of IL-6 mRNA appeared late,it persisted longer;②TNF α levels in the liver,lungs and kidneys were all elevated but to different degrees after shock and resuscitation. At 3 hours after resuscitation,TNF α levels in the three above tissues were still significantly high,while plasma TNF α levels were already decreased to control levels; ③hepatic,pulmonary and renal functions were damaged to different degrees after hemorrhagic shock,with hepatic dysfunction being the most severe; ④endotoxin levels in the liver, lungs and kidneys were markedly increased after shock and resuscitation,and paraIleled the expression of cytokine genes. In addition,there was slgniflcant correlatlon between changes in endotoxin level in tissues and TNF α release in tissues during early shock. lt is suggested that expression and release of cytokines in vital organs might play an important role in local organ damage after hemorrhagic shock,and production of cytokines is related to endotoxin translocation. This study was designed to systematically investigate expression of TNFα, IL-1β, I1-6 mRNA in the liver, lungs and kidneys, release of TNFα in the above tissues, their relationship with hepatic, pulmonary and renal dysfunction, and distribution of endogenous endotoxin in tissues after hemorrhagic shock in mice and rats, with reverse-transcription-polymerase chain reaction, ELISA, etc, to elucidate the kinetics of expression and release of major cytokines in vital organs, their role and mechanism of production in shock. Results were: ①expression of TNFα, IL-1β, IL-6 mRNA in vital organs than increased after hemorrhagic shock and resuscitation, and TNFα expression was the first to appear next by IL-1β. Although expression of IL-6 mRNA TNFα levels in the liver, lungs and kidneys were all elevated but to different degrees after shock and resuscitation. At 3 hours after resuscitation, TNFα levels in the three above tissues were sti ll significantly high, while plasma TNFα levels were already decreased to control levels; ③hepatic, pulmonary and renal functions were damaged to different degrees after hemorrhagic shock, with hepatic dysfunction being the most severe; ④endotoxin levels in the liver, lungs and kidneys were markedly increased after shock and resuscitation, and paraIlled the expression of cytokine genes. In addition, there was slgniflcant correlatlon between changes in endotoxin level in tissues and TNF alpha release in tissues during early shock. lt is suggested that expression and release of cytokines in vital organs might play an important role in local organ damage after hemorrhagic shock, and production of cytokines is related to endotoxin translocation.