BACKGROUND Anemia is a known risk factor for ischemic heart disease. Based on knowledge of the physiologic role of oxygen delivery to the myocardium, anemia may be a cause of more severe cardiovascular diseases or a marker of other processes occurring in the body that induce more severe disease. OBJECTIVE To investigate the relationship between anemia and the clinical picture of IHD, including manifestations, severity and complications. METHODS The population studied comprised 417 similarly aged patients with IHD and anemia. The patients were categorized into subgroups of IHD according to disease severity: namely, angina pectoris, acute ischemia, acute myocardial infarction, congestive heart failure or cardiac arrhythmias. Two populations served as control groups: patients with anemia but no IHD (C-I) and patients with IHD without anemia (C-II). A standard anemia workup was conducted in all patients with IHD and anemia and a correlation was made between the hematologic parameters and the manifestations and complications of IHD. RESULTS The common presenting symptom was chest pain in the study group and in C-II (94% and 86% respectively) and weakness (90%) in C-I. Patients with IHD and anemia tended to suffer from a more advanced degree of IHD (80%) compared to patients with IHD alone who had milder disease (46%). Hematologic values including hemoglobin, mean cell volume, serum iron and total iron-binding capacity correlated inversely with disease severity among anemic patients with IHD. There were significant differences between the study group and C-II regarding CHF (31% and 18% respectively) and arrhythmias (41% and 16% respectively). The mortality rate was higher in patients with IHD and anemia than in patients with IHD alone (13% and 4% respectively). CONCLUSIONS Anemia is a significant risk factor in IHD. It correlates with advanced IHD, CHF, rhythm disturbance and higher mortality rate. An aggressive therapeutic and preventive approach might improve the outcome of this disease.