Meta-analyses of major outcome trials have demonstrated that the benefits of antihypertensive treatment for reduction of the incidence of stroke are entirely consistent with the benefits predicted from epidemiologic data; however, there remains a shortfall in the expected reduction of the incidence of coronary heart disease. Several explanations have been proffered to account for this shortfall, including the potential deleterious metabolic effects of long-term antihypertensive treatment; this has led to the speculation that antihypertensive agents with beneficial ancillary properties might confer additional significant advantage. However, with the exception of the angiotensin-converting enzyme inhibitors, few of these agents have translated into clinical benefit for humans. In addition, sound reasons exist to justify a focus on maintaining and improving the "quality" of blood pressure control. Current evidence suggests that optimal benefit is likely to result from the use of pharmacologic strategies that lower blood pressure consistently over a 24-hour period while at the same time maintaining the "normal" circadian pattern of blood pressure. This result will only be achieved with drugs and drug regimens that genuinely offer long duration of action with the additional potential benefit of maintaining a significant blood pressure lowering effect beyond the end of the dosage interval. This factor is particularly important because many patients with hypertension demonstrate poor adherence to prescribed dosage regimens.