AbstractLisander, B. and J. Martner, Cerebellar suppression of the autonomic components of the defence reaction. Acta physiol. scand. 1971. 81. 84–95.Experiments were performed on anesthetized‐curarized cats, where both the hypothalamic defence area and the cortex of the anterior cerebellar lobe could be stimulated while blood pressure, heart rate and muscle blood flow were recorded. Cerebellar stimulation which, when performed alone, had only insignificant cardiovascular effects, considerably reduced the increases in heart rate, blood pressure and muscle blood flow elicited by standardized defence area stimulations. The cerebellar suppression of the muscle vasodilatation appeared to be due to an interference with the cholinergic vasodilator fibre activation as elicited from the defence area. Thus, after complete pharmacological blockade of all adrenergic effects on the cardiovascular system, defence area stimulation still caused a marked, atropine‐sensitive muscle vasodilatation but this dilatation could be reduced by comcomitant cerebellar stimulation. In contrast, even strong activations of the baroreceptors did not interfere with the vasodilator fibre discharge as elicited from the defence area.Therefore, while the inhibitory baroreceptor reflex and the defence reaction because of their differentiated interaction act in synergism from the hemodynamic point of view (see Kylstra and Lisander 1970) the cortex of the anterior cerebellar lobe tends to suppress the defence reaction by exerting an inhibitory influence on essentially all the autonomic components of this response pattern.