Reviewed in the present article are over 150 family history studies of essential hypertension. By comparing normotensive individuals with and without a family history of hypertension, these investigations seek to identify potential pathophysiologic factors that predate the development of high blood pressure. The research literatures summarized here represent four general areas: 1) cellular salt transport mechanisms, 2) dietary sodium, intravascular volume, and renal function, 3) cardiovascular morphology and physiology, and 4) cardiovascular reactivity. There is strong evidence of early cardiac morphologic changes (greater left ventricular wall thickness and mass) and altered peripheral vascular capacity and responsivity to pressor stimuli among normotensive individuals with a positive family history. In contrast, cardiac output, sodium consumption, intravascular volume, and cardiovascular responses to isometric exercise and standing do not differ in persons with and without a family history of hypertension. Other articles are characterized by inconsistent results, which may be a reflection of the heterogeneity of essential hypertension, but also may be due to methodological weaknesses. The latter include failure to confirm the blood pressure status of ostensibly hypertensive or normotensive family members and the use of relatively weak study designs (eg, where a positive history is defined by a single, hypertensive first-degree relative).