One hundred patients suffering from sustained arterial hypertension were studied over a period of two years during which time the action of parenterally administered hydrogenated ergot alkaloids (Hydergine) constituted the main drug therapy. An immediate transient reduction of both the arterial blood pressure and the pulse rate was demonstrated in over 80 per cent of the entire group within a period of two hours. The average reduction in systolic and diastolic pressure was 36 mm. and 12 mm., respectively, and the pulse rate was reduced 6 beats per minute. Of interest was a group of 22 patients presenting evidence of early central vascular derangement in whom these alkaloids seemed to accomplish their best therapeutic action and possibly aborted what may have been a sustained cerebral accident. Untoward effects were minimal because of rapid dissipation of the drug, and its use in all types of hypertensive disease was deemed safe in the recommended dosage.