About half of patients with symptoms and signs of heart failure will be found to have a normal or near-normal left ventricular ejection fraction (LVEF). These patients are mostly elderly women, and the majority have a history of hypertension in contrast to a predominantly ischaemic aetiology in those with heart failure and a reduced ejection fraction (HFREF). Heart failure with a normal ejection fraction (HFNEF) is proving to be intriguing with only a few established facts but many myths. First, the precise underlying pathophysiology is still debated. Recent work has demonstrated that abnormalities exist in LV systolic properties, ventricular–arterial coupling, LV diastolic function, torsion or twist, ventricular–ventricular interaction, pericardial constraint, with impaired chronotropic, vasodilator reserves and pulmonary hypertension. Thus, the term HFNEF is preferred rather than diastolic heart failure (DHF) as the term DHF implies that the primary or dominant abnormality is in diastole alone to which treatment should be targeted, which may be misguided. Second, the prognosis appears to be similar in both HFNEF and HFREF. Third, dichotomising heart failure into systolic and diastolic clinical entities based on the LVEF has led to a paucity of clinical trials of treatments for HFNEF. Over the past 20 years, significant advances in drug and device therapy have improved survival in patients with HFREF, yet evidence-based treatment for reducing cardiovascular mortality and morbidity in HFNEF is lacking. Finally, on present trends, HFNEF may become the most common form of heart failure and thus a major health problem for which there is little of proven therapeutic value, although some doubt how common true HFNEF is. There is, therefore, an urgent need for coordinated efforts to examine this apparently common condition.