Noncompliance with treatment has long been the plague of the national health-care system. Each year it is estimated that noncompliance with medication costs the UK economy billions of pounds, as a result of preventable hospital admissions and loss of productivity due to illness. In addition, noncompliance has been identified as the predominant reason for the failure of medical therapy and disease progression. Compliance has been defined as 'the extent to which a person's behaviour coincides with medical care or advice'.1 In the management of hypertension, figures from the United States suggest that noncompliance with medication may be as high as 50-80%, with compliance decreasing rapidly over time. 2,3 Based on the current definition of hypertension (blood pressure (BP) of X140/90 mm Hg), 4 the 1998 Health Survey for England revealed that 42% and 33% of adult (X16 years) men and women, respectively, were hypertensive.5 Fewer than 10% of all UK hypertensive patients currently achieve the recommended target BP of o140/90 mmHg, 6,7 despite the well-known risks associated with hypertension and the overwhelming evidence from numerous clinical trials of the benefits of antihypertensive medication. A recent study, based on a meta-analysis of 61 prospective BP studies, calculated that if all hypertensive patients in the UK reduced their systolic BP to o140 mmHg, approximately 21 400 stroke deaths, 41 400 ischaemic heart disease (IHD) deaths, and 125 600 events (nonfatal stroke or IHD) could be prevented each year.7 Why then, in the face of such overwhelming evidence of the benefits of BP reduction, are less than one in 10 people in the UK achieving adequate control of their BP?Various explanations have been proffered to explain why such a large percentage of patients have resistant hypertension, including secondary hypertension and endogenous resistance to treatment. However, the main reason for inadequate control of BP is poor compliance with the treatment regimen, both pharmacological and behavioural (eg, weight reduction, sodium intake restriction, and exercise). Understanding the reasons for patient noncompliance with antihypertensive medication is essential if BP is to be more effectively managed. Table 1 presents some possible factors contributing to noncompliance with medication regimens.Much of the earlier research focused on identifying patient characteristics of noncomplaint individuals and the complexity of the medication regimen. BP control typically requires more than one antihypertensive medication and the frequency of dosing may vary. The complexity of the drug regimen effects compliance; compliance among hypertensive patients improves considerably when drugs are prescribed just once a day. 8 In addition, many patients experience unpleasant side effects from their medication that may be unacceptable in a largely asymptomatic disease. This is often reported as one of the main reasons for non-or partial compliance.9-11 However, more recent studies have focused on patient's decisions and the complex relation...