More than 50% of patients with mild uncomplicated hypertension will need combination therapy to reach target blood pressure, as defined by the Joint National Committee. This percentage is even higher in hypertensive patients with diabetes, renal impairment and congestive heart failure in whom target blood pressures are lower. Combination therapy of angiotensin converting enzyme inhibitor and low dose diuretic offers distinct advantages in the treatment of essential hypertension. The two drug classes may have a synergistic effect on hypertensive target organ disease and blood pressure. Triple therapy with a calcium antagonist may be needed to achieve blood pressure control in more severely hypertensive patients.