Background: the National Heart, Lung, and Blood Institute, through the Joint National Committee on the Detection, Treatment and Control of Hypertension (JNC 7) has recommended that most hypertensive patients begin therapy with a diuretic and sequentially add other classes of drugs until blood pressure is controlled. This approach appears to assume homogeneity in the mechanism by which BP is controlled in different patients. When this standardized strategy has been rigidly applied in Clinical Trials, a majority of patients generally require 2 or more agents to achieve blood pressure control.