BACKGROUND Despite the clear recognition that blood pressure does not remain at the same level over a 24-h period, normally falling during sleep and rising during times of physical or mental activity, a single blood pressure measurement gained during the working day is conventionally used to classify a patient as normotensive or hypertensive. ANTIHYPERTENSIVE TREATMENT AND 24-H BLOOD PRESSURE CONTROL: There is still no definitive proof that antihypertensive drugs providing full 24-h blood pressure control will lead to improved outcomes compared with drugs that provide incomplete 24-h blood pressure control. However, there is a large body of evidence showing that cardiovascular target-organ damage is correlated with 24-h blood pressure measurements and supportive evidence that a fall in these 24-h measurements can predict a likely reduction in cardiovascular target-organ damage. CONCLUSIONS In deciding which antihypertensive agent to use, physicians should select, where possible, those agents that provide blood pressure control through the 24-h period.