When patients with essential hypertension are classified into three major subgroups according to their plasma renin levels, they appear to exhibit different physiologic and epidemiologic characteristics. The present study extends previous observations which have suggested that low renin patients are relatively protected from development of heart attacks and strokes. Low renin patients despite the fact that they are older, exhibit lower blood urea levels than patients in the other two groups. These data are in keeping with the idea that low renin patients have relatively less renal vascular involvement. Young hypertensive blacks, known to be most prone to severe hypertension with vascular complications, practically always fall into the normal renin subgroup, whereas, in contrast, a vast majority of those blacks above the age of 50, with relatively milder hypertensive disease, exhibit low renin levels. These new findings which further associate vascular sequellae with the normal or high renin state provide more support for the concept that low renin patients have a relatively benign type of hypertensive disease. Nonhomogeneity of the low renin hypertensive population and differences in methodologic and physiologic approaches used to define such patients may provide the basis for conflicting observations from certain laboratories.