Anemia is common in heart failure patients but its prevalence varies widely according to various sources. There is no agreement regarding the definition of anemia to be used and several risk factors have been found to be associated with higher prevalence of anemia in heart failure patients. The prevalence of anemia depends on its definition and the clinical characteristics of the patients included in the studies. Anemia is associated with adverse prognosis in the general population, in patients with end-stage renal disease, chronic diseases, coronary artery disease and also in patients with heart failure; however, despite all the information available, the issue of whether anemia is an independent predictor of mortality and the nature of the risk between anemia and mortality in heart failure patients are not yet fully understood.