Several aspects of studies of hypertension suggest that the inception of essential hypertension may occur in the pediatric population. Some of these factors pertinent to the proposed studies include the following: a) Blood pressure in children aggregate in familial patterns. b) Hypertension similarly exhibits familial aggregation. c) Hypertension is more frequent in the adult Black population, with a correspondingly increased mortality rate. The proposed research is directed towards: a) Determining the incidence of hypertension in the adolescent Black population. b) Ascertaining the pattern of familial hypertension. c) Using quantifiable aspects of the renin-angiotensin-aldosterone axis, as a system of physiologic classification, study the applicability of such measurements to the study of genetic heterogeneity of hypertension.