In the blood serum of 93 patients with various localities of the malignant process, the content of nitric oxide (NO), indicators of lipid peroxidation (POL): superoxide dismutase (SOD), malondialdehyde (MDA) and glutathione in red blood cells were determined. 9 patients with ovarian cancer were examined during chemotherapy (6 courses), 40 patients with colon cancer, previously operated, were with malignant liver damage. In 39 patients with anemia, NO indicators were compared with the level of interleukin 6 (IL-6) and hepcidin-25 (GP-25). As a control, 60 practically healthy individuals were examined. It was shown that the NO content was significantly reduced in 69.7% of patients, regardless of the location of the primary tumor. There was a gradual increase in the NO content before each course of chemotherapy. A high concentration of NO (more than 22 µM) was detected in 22 patients with functional iron deficiency (FJ) against the background of anemia of chronic diseases (AHZ), which was accompanied by hyperexpression of IL-6 (27.0±10.5 pg/ml) and GP-25 (25.2±7.1 ng/ml). In contrast, the lowest NO values (less than 22 µM) were observed in 17 patients with IDA. There is no doubt that there is a certain relationship between the development of oxidative stress with the accumulation of highly toxic lipoperoxidation products that affect the overall homeostasis of the body, and the development of anemic syndrome.