This was done to measure the plasma catecholamine concentration esp. norepinephrine and epinephrine in the volunteers and in the operated patents after administration of thiopental sodium, after administration of pancuronium and after the inhalation of halothane. Also studied was the interrelation between blood pressure and pulse rate and catecholamine. Ten healthy subjects were studied under general anesthesia. When compared with the results from patients in the operating room. 1) In the operating room, plasma norepinephrine levels increased 55+/-7.2. pg/ml; The increase int plasma epinephrine was not statistically significant: The increases of the systolic and diastolic pressure were significant : The increase in heart rate was not significant. 2) After the administration of thiopental sodium, plasma concentration of norepinphrine was not significantly increased: the change of plasma eninephrine was not significantly decreased: the increase in systolic and diastolic pressure was less marked: the increase in pulse rate was significant. 3) After the administration of pancuronium, plasma norepinephrine levels were not increased significanty: the decrease in plasma epinephrine was not significant: the increase of systolic pressure was not significant: the diastolic pressure and pulse rate were significant. 4) After the inhalation of halothane, plasma norepinephrine and epinephrine concentration increased significant and the change of the pulse rate was significantly increased.