Thyrotropin—releasing hormone (TRH) is a tripeptide amide released by the hypothalamus of mammals. It can antagonize many actions of β—endorphin but not its analgesic effect. Holaday et al² reported that TRH could reverse the pathological progress of endotoxic and hemorrhagic shock in 1981. We have carried out a series of experimental studies on the effects and mechanisms of the antishock property of TRH since 1984. All the findings are systematically reviewed in this paper. It was found that TRH given intravenously, intraarterially or intracerebroventricularly exerted beneficial effects on different types of circulatory shock (hemorrhagic, traumatic and endotoxic) in dogs, rabbits and rats. TRH could improve the hemodynamics, cardiac contractility, microcirculation, blood gas, certain biochemical indices, survival rate and survival time of the shock victims. So it is believed that TRH is superior to anisodamine in the treatment of circulatory shock. On the basis of our findings, the mechanisms of the antishock property of TRH are Inferred as follows: 1. Sensitization of the β—adrenoceptors. 2. Direct activation of the cardiovascular centers such as the rostral ventrolateral medulla. 3. Alleviation of lipid peroxidation damage induced by oxygen—derived free radicals. 4. Improvement of the oxidative phosphorylation of the mitochondria during shock. 5. Increase of the cellular cAMP level during shock and regulation of the cellular metabolic function. 6. Improvement of the circulation of the vital organs. In a word, TRH is a promising agent for antishock therapy.