Glycopyrrolate(Robinul) is a potent anticholinergic drug. Being a quaternary ammonium compound, it dose not cross the blood-brain barrier and thus dose not have the central effects. It has been shown that glycopyrrolate has a pharmacologic properties similar to that of atropine, belladonna alkaloid, but it has lesser effect on the heart rate than that of atropine. The author administered a small dose of glycopyrrolate intravenously to 18 people who were awake, 21 compatous cases and 17 halothane anesthetized cases. The effect on the heart rate in these 3 groups was compared. The results are as follows: 1) In the awake state, glycopyrrolate(0.1mg) produced a slight decrease in the heart rate. 2) In the comatose state, glycopyrrolate(0.1mg) produced a slight increase in the heart rate. 3) In the halothane anesthetized state, glycopyrrolate(0.1mg) produced a significant increase in the heart rate. 4) In the comatose state, the absence of bradycardia after a small dose of glycopyrrolate is similar to a small dose of atropine. Therefore we suggest that bradycardia after glycopyrrolate and atropine is caused by sympathetic ganglion block.