Background: In addition to hematopoiesis, iron plays an essential role in numerous biological processes that maintain homeostasis. Patients with heart failure (HF) are prone to developing iron deficiency (ID). Aims of the Study: To investigate the prevalence of iron deficiency and factors affecting this deficiency in patients with heart failure. Patients and Methods: This cross-sectional study included 100 patients diagnosed with HF at admission (50 men and 50 women). Another 100 age- and sex-matched apparently healthy subjects were recruited to represent the control group. The following parameters were investigated for each participant: serum ferritin, transferrin saturation, haemoglobin (Hb), complete blood count, and hematocrit. Results: Patients with HF showed significantly higher frequencies of absolute ID, anaemia, and ID anaemia (41%, 52%, and 34%, respectively) than controls (17%, 17%, and 8%, respectively). In multivariate analysis, the female gender (OR= 2.81, 95%CI= 1.18-14.8, p= 0.028), anaemia (OR= 9.49, 95%CI=1.88-18.73, p<0.001), and mean cell volume (MCV)< 80 (OR= 3.8, 95%CI= 1.07- 22.34, p= 0.044) were independent predictors of ID in patients with HF. Conclusions: Absolute ID is much more prevalent among HF patients. Each of the female gender, anaemia, and low MCV is an independent factor that could predict the occurrence of ID. It is recommended to assess iron levels in each patient with HF, and to provide appropriate iron supplementation to correct ID when present.