In many patients with malignant haematological and oncological diseases during the disease the haemoglobin concentration declines. Anaemia can be due to blood losses, less frequently to nutritional deficiency. One of frequent causes is the humoral effect of malignant disease on haematopoiesis and the development of anemia of chronic disease. Anemia of chronic disease has a complex etiology. Decreased production of erythropoietin is one of the participating factors and the pharmacological doses of erythropoietin can restore the number of erythrocytes to normal value. The authors present basic information on chronic anaemia of malignant diseases and principles of erythropoietin treatment of these patients.