Numerous studies over the past few years have indicated that mechanisms of pressure elevation are not uniform in all patients with essential hypertension. Simple clinical findings such as age, sex, body habitus, and race often allow us to define the predominant pathogenetic mechanism. Not only is the hemodynamic and biochemical pattern of essential hypertension different in patient subgroups, but manifestations of target organs and therefore the risk of cardiovascular disease also vary distinctly from one group to another. Identifying the predominant hemodynamic, biochemical, and target organ disease pattern in a given patient will help the physician to select more specific antihypertensive therapy and thereby, it is hoped, prevent or reverse target organ disease and improve the quality of life.