In acute experiments on anaesthetized dogs, the haemodynamic effect of etacizine (0.5 and 1.0 mg.kg-1 i.v.) and lidocaine (2.5 and 10 mg.kg-1 i.v.) were compared. Etacizine produced a decrease in heart rate and a temporary decrease in myocardial contractility. After the dose of 1 mg.kg-1 there occurred a temporary increase in peripheral vascular resistance. It did not affect aortal blood pressure, systolic and minute output volume of the heart. Lidocaine produced a decrease in heart rate, aortal blood pressure, systolic and minute output cardiac volume with a rapid return to the original values. Besides this negative effect it was possible to observe an increase in the minute output volume and peripheral vascular resistance with larger doses, which gives evidence of the central effect of the drug.