Objective: to study the importance of cytokines, hepcidin, a soluble transferrin receptor, iron metabolism in the development of anemia of chronic diseases in patients with malignant neoplasms and rheumatic pathology, to identify the leading factors in the development of anemia for each of the studied groups and to develop a working classification of anemia of chronic diseases.Materials and methods. 63 patients with rheumatic pathology were examined. The study group included 41 (17 men/24 women, average age 53.4 ± 4 years) patients with anemia, the control group included 22 (9 men/13 women, age 49.3 ± 1.78 years) patients without anemia. The patients (n = 63) with stage II–IV malignant neoplasms were examined. The study group included 41 patients with anemia (34 men/7 women, age 67.1 ± 9.9 years), in the control group 22 patients without it (17 men/5 women, age 60.2 ± 14.9 years). The number of red blood cells, the hemoglobin level, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, concentrations of serum iron, total iron binding capacity (TIBC), ferritin, transferrin, C-reactive protein (CRP), transferrin saturation index (TSI), and soluble transferrin receptor (sTfR), hepcidin, interleukin (IL) – 6, – 10, tumor necrosis factor-α (TNF-α) were determined. Mann – Whitney U Test was applied to check for statistically significant differences in study samples.Results. Compared with the control group, elevated concentrations of ferritin, CRP, hepcidin, sTfR and IL-6 (p <0.05) were found for patients with rheumatic pathology and anemia and no differences were found in the concentrations of iron, TIBC, TSI, transferrin. For patients with solid malignant neoplasms and anemia, lower concentrations of iron, TIBC, TSI and higher concentrations of CRP, hepcidin, sTfR, IL-6, IL-10, TNF-α (p <0.05) are shown in comparison with the control group and there were no differences in the concentrations of ferritin, transferrin (p >0.05).Conclusion. The multicomponent anemia genesis in patients with cancer and rheumatic pathology is shown. The contribution of each mechanism to the development of anemia may vary depending on the specific nosological form. In patients with cancer, functional iron deficiency, activation of IL-6, IL-10, TNF-α synthesis and an increase in hepcidin synthesis lead to the development of anemia of chronic diseases. In patients with a rheumatic profile and anemia, a more pronounced synthesis of hepcidin and an increase IL-6 concentration are indicated. A working version of the classification of anemia of chronic diseases based on the leading pathogenetic factor is proposed (with a predominant iron deficiency, with impaired regulatory mechanisms of erythropoiesis, with insufficient production of erythropoietin).