Hypertension is now seen as a broader condition than high blood pressure alone. Large-scale epidemiologic studies have established that high blood pressure is associated with an increased risk of cardiovascular events, but clinical trials of antihypertensive therapy have shown an inconsistent reduction in major cardiovascular endpoints. Importantly, the incidence of coronary disease has been reduced to only a small extent, suggesting that factors beyond high blood pressure are important in the genesis of atherosclerotic disease in hypertensive patients. It is evident, for example, that patients with hypertension have an exaggerated vulnerability to the consequences of lipid abnormalities. Moreover, it has recently been established that hypertension is characterized by insulin resistance and altered glucose tolerance. As a result, high plasma concentrations of insulin produce proliferative effects on vascular smooth muscle and connective tissue, and they may adversely affect the lipid profile. The left ventricle is also involved in hypertension--independent of blood pressure. There is growing evidence that there are increases in the muscle mass of the left ventricle and changes in its diastolic filling characteristics at the very early stages of hypertension. The arterial circulation is similarly involved, for alterations in structure or function, reflected by diminished arterial compliance, can be demonstrated prior to the appearance of clinical hypertension. Treatment designed to protect hypertensive patients from cardiovascular events must not only be based on blood pressure, but must take into account all the components of the hypertension syndrome.