Candesartan is a selective angiotensin II Type I (AT(1)) receptor blocker which binds tightly to, and dissociates slowly from the receptor. It is an effective, long-acting antihypertensive agent with few or no side effects, when compared to placebo in hypertension trials. Several studies indicate that candesartan might prevent diabetes. A research programme of three prospective randomised outcome trials (the CHARM [Candesartan in Heart Failure Assessment of Reduction in Mortality and Morbidity] programme) has shown that candesartan is of clinical value in a broad spectrum of patients with symptomatic heart failure, regardless of background therapy and ventricular function. There is a clear benefit of candesartan in patients unable to tolerate an angiotensin-converting enzyme inhibitor (ACEI) and this benefit is of a similar magnitude to that obtained with an ACEI. CHARM-Added shows that symptoms, morbidity and cardiovascular mortality are further reduced if an AT(1)-receptor blocker is added to an ACEI. This benefit is not only statistically significant but also clinically important. CHARM-Preserved indicate that candesartan can reduce hospital admission for heart failure in patients with preserved systolic function.