Aim To evaluate the dynamics of indexes of oxidative stress and markers of myocardial injury and dysfunction in patients with aggressive type lymphomas during the antitumor therapy.Material and methods This study included 75 patients with lymphoproliferative diseases of aggressive type. The main group consisted of 53 patients who received one course of antitumor therapy during the study. The comparison group consisted of 22 patients who have not received any specific treatment so far. Troponin I (TnI), high-sensitivity troponin (hsTnI), heart-type fatty acid binding protein (Н-FAВР), N-terminal pro-brain natriuretic peptide (NT-prоBNP), superoxide dismutase (SOD), and myeloperoxidase (MPO) were measured in patients of both groups at baseline, and in the main group, they were measured at 4 hours after administration of antitumor agents and on completion of the course. Functional status of the cardiovascular system was evaluated by electrocardiography in all patients at baseline and after the course of antitumor treatment and by echocardiography.Results The chemotherapy was associated with increased levels of NT-prоBNP, SOD, and MPO (30.670±15.367 vs. 52.309±25.718 pmo l/l; 1.61±0.135 vs. 1.74±0.193 U/ml; and 507.54±91.51 vs. 742.3±49.01 ng/ml, respectively). The study results indicated activation of oxidative stress on the background of the administered antitumor therapy, progressive myocardial dysfunction, and increased frequency of arrhythmic episodes.Conclusion The study results allowed identifying NT-prоBNP, MPO, and SOD as important indexes for determining a patient group at high risk of cardiotoxicity during the antitumor treatment.