The effects of glycopyrrolate 10 microgram kg-1 i.v. given at induction of anaesthesia were compared with those of atropine 20 microgram kg-1 i.v. given at induction and oral atropine 30 microgram kg-1 given 90 min before operation. Antisialagogue effect, changes in axillary temperature, heart rate, frequency of cardiac arrhythmia and postoperative restlessness were determined. Patients who had received oral atropine had more pharyngeal secretions, a lower heart rate and a greater frequency of cardiac arrhythmia than when either atropine or glycopyrrolate was given i.v. Secretions were significantly less during operation when i.v. glycopyrrolate was used.