Experimental hypertension of a persistent type is regularly produced by the application of a specially designed adjustable silver clamp so as to constrict both renal arteries or by constriction of one renal artery and excision of the opposite kidney. This leads to elevated blood pressure without or with only little depression of the excretory function of the kidney.1The comparable human essential hypertension is, in its early stages at least, also without accompanying decrease of renal excretory function, but as it progresses renal insufficiency may develop. The kidneys of such patients show arteriolar sclerosis of varying degrees of intensity and distribution. In some instances renal arteriosclerosis or other chronic disease of the kidney may be the determining factor. In experimental hypertension produced by this method and in human essential hypertension a common feature is alteration of renal circulation. The following report is an evaluation of various forms of treatment,