Heart failure is the cause of an increasing number of hospitalizations and is one of the leading causes of death in the world, especially in Western countries. Iron deficiency, with or without anemia is a common comorbidity and a potential therapeutic target in patients with heart failure. In an effort to establish the interrelationship, in the period from September 1 to December 1, 2019, we analyzed the medical history of 150 patients hospitalized due to decompensated heart failure. A high prevalence of anemia and iron deficiency was found among hospitalized patients, and men were, in both cases, more prevalent. Also, the incidence of absolute iron deficiency, which correlates with a more severe clinical presentation, was higher than functional iron deficiency. By comparing the values of basic clinical characteristics and laboratory parameters in patients with and without iron deficiency, hospitalized for heart failure, we found significantly higher values of heart rate (p=0.016) and serum creatinine (p=0.046) in the first group. On the other hand, statistically significantly lower values of serum iron (p=0.045) and ferritin (p<0.001) worsened the already impaired quality of life of patients with iron deficiency. Reduced renal function in iron deficiency patients justified renal injury as an important comorbidity in heart failure (cardiorenal syndrome). Considering altered renal function, patients with iron deficiency received significantly less ACE-I (p=0.049). The overall mortality was 16.7% in patients hospitalized for heart failure.