The effects of intramuscular injection of atropine (0.6 mg), hyoscine (0.4 mg) and a placebo have been compared as premedication. Atropine did not differ from the placebo with regard to sedation and relief of apprehension but did produce a higher incidence of tachycardia. Hyoscine produced a high incidence of good or fair sedation and a very low incidence of tachycardia. The relative slowing of the heart compared with the placebo may be because of the good sedation or may be a specific: action of the drug. Anaesthesia with methohexitone and nitrous oxide showed a higher incidence of excitatory phenomena after hyoscine than after atropine. Respiratory upset (hiccough) was reduced by hyoscine, as was the incidence of emetic sequelae in the first hour after anaesthesia.