The benefits of BP reduction are undisputed, and management guidelines are well established. Nevertheless, epidemiological studies and randomised clinical trials have consistently shown that, although treated, BP frequently remains inadequately controlled. This failure to control BP adequately is not fully recognised by physicians or their patients. Furthermore, even when BP control is not achieved, there is evidence that many physicians do little to modify therapy. This gap between theory and practice in the control of hypertension is a multifactorial phenomenon. Patients may not take medication or adhere to their physician's advice; physicians appear satisfied with sub-optimal therapy; the underlying pathophysiology of hypertension is heterogeneous and thus it can be difficult to predict which patients will respond to a specific treatment; there is poor communication between physicians and their patients; and treatment guidelines may be too complex, theoretical and unclear to be followed in general practice. Despite these difficulties, it is clear that BP control can be improved by combining several antihypertensive drugs. This requires careful consideration with regard both to the mechanisms of action of the agents selected and their tolerability.