Many studies have shown the importance of antihypertensive drug therapy as a factor in reducing the risk of cardiovascular morbidity and mortality, and in containing the cost of managing hypertension and its complications. Nevertheless, the evidence in clinical practice indicates about half of hypertensive patients do not receive pharmacological treatment and about half of treated patients do not achieve blood pressure level control. Undertreating hypertension is the leading cause of failure in drug therapy effectiveness and cost effectiveness. The pharmacoeconomic burden of undertreating hypertension can be defined as the clinical (number of cardiovascular events) and economic (costs of managing cardiovascular events) consequences that would have been avoided by adequate control of blood pressure levels. In the last few years, the increase in this burden and the restriction of budget constraints has raised the awareness of healthcare providers with regards to the need to achieve better performance and to improve disease management of hypertension. This review aims to present the current situation regarding the pharmacoeconomic burden of undertreating hypertension by identifying the key issues of this medical condition, defining and measuring the extent of undertreatment, defining and measuring costs associated with undertreatment, and discussing some fundamental aspects of disease management for hypertension. The pharmacoeconomic burden of undertreating hypertension appears to be an extremely important phenomenon for which there is currently only very limited adequate research. The present dearth of appropriate data can be largely attributed to the lack of epidemiological studies in clinical practice. Future studies are necessary for a more precise quantification of the therapeutic and economic impact of undertreating arterial hypertension in clinical practice (appropriateness studies) and for more precise selection of antihypertensive drugs on the basis of the different cost-effectiveness profiles detected in 'real world' settings (cost-effectiveness studies).