Over the last 30 years we have gone from famine to feast in terms ofthe epidemiological data now published for heart failure (HF). The field started with the seminal publication on the natural history ofHF from the Framingham study in 1971 showing a prevalence of HF of 0.8% in those aged between 50 and 59, rising to 9.1% inthose over 80 years with incidence rates of 0.2% at age 54 and 0.4% at age 85. This was followed by a large European study,‘The men born in 1913’, which gave similar figures of a prevalenceof 2.1% at age 50 and 13% at age 67 and incidence rates of 0.15% and 1% respectively at ages 50 and 67. These landmarkstudies relied on a clinical diagnosis of HF, basedon symptoms, signs, and scoring systems to identify cases. Moremodern epidemiological studies have used definitions of HF whichinclude objective measures of cardiac function in their definition,in keeping with current European and United States guidelines forthe diagnosis of HF. Initial studies focused on systolic dysfunctionbecause they reported at much the same time as the HF treatmenttrials which also enrolled patients with systolic HF. More recentlyattention has turned to describing the epidemiology of HF withpreserved systolic function, in addition.When describing the epidemiology of HF, it is worth bearing inmind that estimates of incidence and prevalence will vary according to the definition of HF used and the type of cohort being studied.This is especially important when assessing work which hasobjectively measured left ventricular systolic function. Variablessuch as left ventricular ejection fraction are normally distributed,so the cut point chosen is a critical determinant of the eventualresults.The present chapter aims to outline the contemporary epidemiologyof HF by describing its prevalence, incidence, aetiology andmortality as well as describing the trends which are occurring in thearea. It will discuss hospitalization rates, prognosis and economicburden in both Europe and the United States.