Almost half of all patients with heart failure (HF) have preserved systolic function (PSHF) or heart failure with normal ejection fraction (HFNEF). Some of these have valvular abnormalities such as severe mitral or aortic regurgitation, severe anaemia, thyrotoxicosis or rarer tropical causes for heart failure. However, the majority of those with PSHF often have echocardiographic evidence of impaired diastolic function i.e. impaired relaxation and increased stiffness. This diastolic dysfunction may be related to age, hypertension or ischaemia. There is little evidence for any effective therapy in this large HF population despite randomised trials comparing placebo to ACE inhibitors i.e. perindopril in PEP-HF or angiotensin receptor blockers i.e. candesartan in the CHARM Preserved trial. There are also ongoing studies of aldosterone antagonists in diastolic heart failure i.e. eplerenone vs placebo in TOPCAT which continues to recruit.