Glycopyrrolate is frequently administered in combination with neostigmine to reverse a neuromus- cular blockade. The dosage was well established at 1/5 of neostigmine. But the authers have often observed a delayed manifestation of relative bradycardia after such a recommended dosage. This is not mentioned in the literature, but this may be due to an insufficient observation period. The authors monitored the change of pulse rate for 1 hour after the administration of the recom. mended dose. Further, the data wIns compared with that obtained after studies of lower and higher doses. The doses were 0.004, 0.008 and 0.012mg/kg of glycopyrrolate with 0.04mg/kg of neostigmine. 1) At all doses, bradycardia relative to the pre-reversal pulse rate was progressive until 30 minutes after injection. 2) As the glycopyrrate dose was increased the degree of bradycardia decreased (-24.7, -20.5, - 15.0 at 30 min.). 3) There was no difference in the immediate change in the pulse rate between the dcsages of 0.008 and 0.012 mg/kg. Change occured at 9 mins. 4) At dosages of 0.004 and 0.008 mg/kg, the pulse rates at 60 min were comparable to their ward pulses, but at a dosage of 0.012 mg/kg, the pulse rate was 8.5 beats/min higher.