The only antihypertensive treatment regimen with documented effect on morbidity and mortality from stroke and coronary heart disease is based on diuretics and/or beta-blockers. However, new antihypertensive drugs are now widely used. These compounds may also prevent cardiovascular complications, but, as yet, this has not been proven. The clinical trials of the 1990s such as STOP II, CAPPP and NORDIL will test whether antihypertensive treatment with ACE-inhibitors and calcium-blockers are more effective than diuretics and beta-blockers in preventing cardiovascular complications. Also, a large-scale study (HOT) is being undertaken to examine how far diastolic blood pressure should be treated, and whether a small dose of aspirin has a protective effect when combined with good control of blood pressure. These studies will hopefully lead to better guidelines for the future treatment of hypertension.