BACKGROUND. There is enough evidence of the negative impact of excess weight on the formation and progression of res piratory pathology. Given the continuing SARS-CoV-2 pandemic, it is relevant to determine the relationship between body mass index (BMI) and the clinical features of the novel coronavirus infection (NCI).AIM. To study the effect of BMI on the course of the acute SARS-COV-2 infection and the post-covid period.MATERIALS AND METHODS. AKTIV and AKTIV 2 are multicenter non-interventional real-world registers. The АКТИВ registry (n=6396) includes non-overlapping outpatient and inpatient arms with 6 visits in each. The АКТИВ 2 registry (n=2968) collected the data of hospitalized patients and included 3 visits. All subjects were divided into 3 groups: not overweight (n=2139), overweight (n=2931) and obese (n=2666).RESULTS. A higher BMI was significantly associated with a more severe course of the infection in the form of acute kidney injury (p=0.018), cytokine storm (p<0.001), serum C-reactive protein over 100 mg/l (p<0.001), and the need for targeted therapy (p<0.001) in the hospitalized patients. Obesity increased the odds of myocarditis by 1,84 times (95% confidence interval [CI]: 1,13–3,00) and the need for anticytokine therapy by 1,7 times (95% CI: 1,30–2,30).The patients with the 1st and 2nd degree obesity, undergoing the inpatient treatment, tended to have a higher probability of a mortality rate. While in case of morbid obesity patients this tendency is the most significant (odds ratio — 1,78; 95% CI: 1,13-2,70). At the same time, the patients whose chronical diseases first appeared after the convalescence period, and those who had certain complaints missing before SARS-CoV-2 infection, more often had BMI of more than 30 kg/m2 (p<0,001).Additionally, the odds of death increased by 2,23 times (95% CI: 1,05-4,72) within 3 months after recovery in obese people over the age of 60 yearsCONCLUSION. Overweight and/or obesity is a significant risk factor for severe course of the new coronavirus infection and the associated cardiovascular and kidney damage Overweight people and patients with the 1st and 2nd degree obesity tend to have a high risk of death of SARS-CoV-2 infection in both acute and post-covid periods. On top of that, in case of morbid obesity patients this tendency is statistically significant. Normalization of body weight is a strategic objective of modern medicine and can contribute to prevention of respiratory conditions, severe course and complications of the new coronavirus infection.