Annotation. Changes in the complete blood count (CBC) that were recorded in patients against the background of coronavirus infection (COVID-19) attracted the attention of many researchers from the beginning of the pandemic, especially in terms of assessing the prognosis, the severity of the course of the disease in a particular patient. It should be noted that changes in the CBC can be both reactive and systemic response or even reflect the toxic effects of this infection on bone marrow hematopoiesis. The article analyzes the current data in the world literature on changes in CBC against the background of COVID-19 infection to assess their value in the future prognostic sign. To assess the prognosis of the course of the COVID-19 infectious process, a number of peripheral blood indicators were stuck: platelet count, platelet-leukocyte index or systemic inflammation index (ratio of neutrophils × platelets × monocytes to lymphocytes), traditional NLR indices (neutrophil / lymphocyte ratio), PLR (ratio thrombocytopenia / lymphocyte), which with different predictive values indicate the presence of SARS CoV-2 infection, the severity of the course, and the likelihood of a fatal leak or recovery. From the early stages of the disease, COVID-19 is associated with morphological and functional changes in blood cells that are easily detected by conventional haematology analysers, but generalization of the data requires further profiling and multicentre studies. To date, there are no generalized studies on changes in CBC in patients with COVID-19 in the Ukrainian population, which does not allow us to draw conclusions about the features of these changes in this group of patients. It is promising to further study the parameters of peripheral blood in patients with COVID-19 in the Ukrainian population in order to assess reference and prognostic signs and subsequent implementation into practical medical practice.