In recent years, there has been an increase in polymorbidity in therapeutic practice. The clinical symptoms of polymorbidity are quite diverse and nonspecific. Depletion of the neuroimmunoendocrine systems is one of the factors contributing to the development of polymorbidity. The aim of the study was to evaluate the relationship between interleukin-8 levels and cognitive impairment in patients with polymorbidity. Patients complaining of memory impairment were selected after the second stage of an in-depth medical examination of citizens who had recovered from the novel coronavirus infection COVID-19. Inclusion criteria were the presence of three chronic diseases simultaneously in one patient (post-COVID syndrome, type 2 diabetes mellitus, hypertension); signed informed voluntary consent. Exclusion criteria: a history of acute cerebrovascular and coronary circulatory disorders; lymphoproliferative diseases; malignant neoplasms. The study included 22 patients with polymorbidity, including 14 women and 8 men, with an average age of 62.09±8.96 years. Using the multiplex assessment method, the concentration of interleukin-8 in the blood serum was determined to be 8.35 (5.50; 9.33) pg/ml. An analysis of correlation relationships was performed to assess the influence of interleukin-8 concentration on the clinical picture of polymorbidity. Based on the analysis results, a positive correlation was established between the concentration of interleukin-8 and complaints of memory impairment (r=0.663; p=0.002). According to the literature, an increase in the concentration of interleukin-8 was observed in neurodegenerative diseases such as Alzheimer’s disease and vascular dementia. It was shown that cytokines can modulate the function of neurons and glial cells, contributing to neurodegeneration. The data obtained in our study support the role of interleukin-8 in cognitive-related neuroinflammation in polymorbidity.