Annotation. Against the background of active study of the causes, prognosis and problems of choosing optimal methods of surgical treatment of postoperative sternomediastinitis, issues of complex analysis of the causes of occurrence, development of preventive measures, these measures for organizing cardiac surgical care, as well as its everyday effects, have not been sufficiently studied. Goal. Study of modern aspects of development of postoperative sternomediastinitis and analysis of economic effect of this complication. Materials and methods. A multi-stage study implied a comprehensive analysis of the causes and risk factors for the development of postoperative sternomediastinitis, and a clinical and economic observation of the type of cost of illness analysis with a study of the costs of treating postoperative sternomediastinitis with an assessment of the economic effect of this complication. Results. The main causes of postoperative sternomediastinitis can be divided into 3 groups — associated with the preoperative condition of the patient, associated with intraoperative exposure and caused by the internal environment of the medical organization. When analyzing the cost of treatment, the minimum costs for the treatment of a completed case of postoperative sternomediastinitis were 59 390,79 rubles, the maximum — 225 278,00 rubles, the average value — 160 930,14 rubles. The average bed-day for the treatment of postoperative sternomediastinitis was 31,1 days. Conclusion. Postoperative sternomediastinitis has a negative economic impact on the healthcare system, significantly increasing the cost of providing medical care within the full cardiac surgery cycle. Given the availability and high efficiency of measures that can significantly reduce the incidence of infectious complications in cardiac surgery departments, special attention should be paid to the prevention of postoperative sternomediastinitis, which in the long term will allow for budget savings.