The renin-angiotensin system, through the effects of angiotensin II, may be involved in the pathogenesis of essential hypertension and associated left ventricular hypertrophy. Treatment with angiotensin-converting enzyme inhibition (ACEI) lowers blood pressure and reduces left ventricular hypertrophy. ACEI, however, may not completely inhibit the production of angiotensin II and its effects, and adverse effects like cough and rise in creatinine have been associated with ACEI and reduced degradation of bradykinin. The first selective antagonist of the angiotensin II-1 (AT1) receptor, losartan, has recently been approved. The LIFE study has been started, in which 8,300 hypertensive patients with left ventricular hypertrophy in Scandinavia and the USA will be randomized to blinded treatment with either atenolol or losartan to compare the effects on cardiovascular morbidity and mortality over a period of five years.