Hypertension is highly prevalent in developed and developing countries (more than 30% of the adult population when a threshold value of 140/90 mm Hg is selected). It constitutes one of the major cardiovascular risk factors and accounts for more than 5% of total deaths worldwide. The economic impact of hypertension is enormous, representing $US23.74 billion in the US in 1995 and approximately $US1685 million in Spain in 1994. Direct costs amount to more than 50% of the total costs of hypertension, and almost 70% of these are attributable to drug treatment. Furthermore, hypertensive patients use medical services 50% more than normotensive individuals, and hypertension represents one of the 3 leading causes of visits to primary healthcare centres. When considering the cost effectiveness of hypertension treatment, there is no doubt that it is cost effective in comparison with other interventions, although some controversies exist, mainly with respect to mild-to-moderate hypertension and to the long term versus short term benefits. The controversy about the absolute risk of hypertension influences the cost-effectiveness analysis. Because of the limitations of the available cost-effectiveness analyses, it is currently impossible to recommend the use of any particular antihypertensive drug for all patients with hypertension. Consequently, the choice of antihypertensive in any patient should be guided by clinical experience and the recommendations of the present international guidelines.