Anemia is one of the most frequent comorbidities found in patients with coronary artery disease and chronic heart failure (CHF) who are being followed in cardiac rehabilitation facilities. The more frequent type of anemia is caused by iron deficiency (IDA, iron-deficiency anemia): this review summarizes the state of the art of this topic. First of all, the mechanisms of IDA will be analyzed. Subsequently, a description of the main conditions where IDA can unfavorably affect the clinical course, and of its more frequent complications, will be presented (percutaneous interventions, heart surgery, CHF). Special attention will be paid in the description of anemia in the setting of CHF. To this regard, in recent years a relevant amount of research has been carried out, to determine whether treating anemia (either by directly stimulating erythropoiesis or by correcting iron deficiency by oral or intravenous route) is of any clinical and prognostic relevance in patients with CHF. The results of this research will, therefore, be summarized and critically discussed. Finally, we will outline the promising role of cardiac rehabilitation facilities and of its network of experts in the diagnosis, prognostic stratification, and treatment of anemia and iron deficiency.