Purpose: to study the relationship of the indicators of the general blood test with the severity of the course of COVID-19 in hospitalized patients.Materials and methods: the study included 165 patients (92 men — 55.8%, and 73 women — 44.2%, the average age — 59.9 years) who were treated at the Moscow State University Medical Center in the period from April to June 2020 with a diagnosis of COVID-19. All patients underwent: general blood test, CRP, CT of the lungs. The severity of the clinical condition was assessed using the SHOCK-COVID and NEWS-2 scales.Results: a more severe clinical condition of patients and a greater severity of lung damage on admission were statistically significantly associated with a decrease in the number of red blood cells and hemoglobin, as well as with a greater width of the distribution of red blood cells (RDW-SD). The rate of erythrocyte sedimentation (ESR) was significantly associated with the clinical condition of patients evaluated by SHOCK-COVID (r=0.61, p<0.001) and the marker of CRP inflammation (r=0.55, p<0.001). An increase in the absolute number of neutrophils (N), a decrease in the absolute number of lymphocytes (L), and, as a result, an increase in the N/L ratio index was a marker of a more severe course of the disease. It was the N/L index that had the maximum correlation coefficient with the most commonly used marker of systemic inflammation - CRP (r=0.50, p<0.001). The decrease in the level of CRP by discharge was associated with a significant decrease in ESR (r=0.36, p<0.001), the index of the ratio of neutrophil and lymphocyte levels (N/L) (r=0.39, p<0.001), and an increase in the width of the distribution of red blood cells (RDW-SD r=0.25, p<0.01; RDW-CV r=0.57, p<0.001).Conclusions: the most informative indicators of the general blood test at admission to the hospital, allowing to assess the severity of the disease — the width of the distribution of red blood cells, the index of the ratio of neutrophils to lymphocytes and ESR.