SummaryThe author describes the clinical picture of a group cases of essential hypertension characterised by a paradoxical hypotension associated with bradycardia and a paradoxical leucopenia with lymphopenia alter a subcutaneous injection of 1 milligram of adrenalin; further by a paradoxical stimulation of the gastric secretion after a subcutaneous injection of 1 milligram of atropin ; finally by the abolition of the paradoxical adrenalin effect by a previous injection of atropin.The mecanism and the etiology of the paradoxical reactions are discussed. The author means that the picture, for which he proposes the name of«neurotonic hypertension», is based on a permanent state of hypoparasympathicotony.