The diagnosis of hypertension has traditionally been based on clinic blood pressure (BP) but home and ambulatory measurements are better correlated with cardiovascular outcomes. A recent systematic review and cost-effectiveness study found that ambulatory blood pressure monitoring (ABPM) is more accurate than both clinic and home monitoring in diagnosing hypertension. A diagnostic strategy for hypertension using ABPM, following an initial raised clinic reading, would reduce misdiagnosis and be cost saving for the NHS. Only about one in every twenty diagnoses is made with an ABPM machine, and these are largely confined to larger GP practices and specialist units.