Abstract: In anesthetized dogs, the blood pressure dropped abruptly after iv injection of fluorocarbon emulsion 0.1ml/kg and returned to control level in 30～40 minutes. Remarkable tachyphylaxis appeared after repeated injection of the emulsion. When the emulsion was infused intravenously to rats at a dose of 30 ml/kg, the blood presure and heart rate were slightly decreased. However, in cats and rabbits after iv of the emulsion, 10 ml/kg no significant hypotensive reaction was noticed.When the emulsion t (10 ml/kg) was intravenously injected to normal rabbits, the left ventricular pressure and myocardial contractility were not significantly influenced. In cats and dogs, during the hemorrhagic hypovolemic period, hemodynamic changes were observed with marked reduction of blood pressure, left ventricular pressure, stroke volume, cardiac output, and myocardial contractility. All of the above mentioned parameters were restored and reached control values after replacement with fluorocarbon emulsion.Intravenous injection of fluorocarbon emulsion at 25 or 50ml/kg prolonged significantly the survival time of mice (56% and 100%) under normobaric hypoxia condition.