Introduction. The background of cardiovascular system’s state study in patients with syphilis/HIV co-infection is determined by increasing of co-infection cases in recent years and by data about cardiovascular pathology, caused by each of these infections. In syphilis it is characterized by development of mesaortitis with complications in the form of aortic valve damage, coronary ostial stenosis and aortic aneurysm. In HIV infection it is an infective endocarditis, pericarditis, pulmonary hypertension and dilated cardiomyopathy. Myocarditis with subsequent dilated cardiomyopathy can develop in either syphilis or in HIV infection. Objective. To reveal cardiovascular pathology in patients with syphilis/HIV co-infection. Results and discussion. The clinical case of severe cardiac pathology in 52 years old man, that was monitored in dynamics and characterized by significant decrease of myocardial contractility with dilated cardiomyopathy development and with a critical reduction of left ventricular ejection fracture (up to 20%, when normal indicator is more than 55%), was described. At the same time, there was a maintenance of physical activity (regular exercises) and a certain tendency to improvement of objective instrumental indicators of patient. The correlation of cardiac pathology with syphilis and HIV infection against the background of antiretroviral therapy is discussed. Conclusion. The features of cardiovascular pathology revealed in patient are directly associated with syphilis/HIV co-infection. The regular administration of antiretroviral therapy and the patient’s maintenance of physical activity are positive factors, that counteract the progression of cardiac pathology. © 2023, Media Sphera Publishing Group. All rights reserved.