In Ukraine, more than 3.5 million cases of COVID-19 have been registered during the pandemic, and the death toll is almost 90,000. Ukraine is a leader in Europe in the growth of new cases of COVID-19 and mortality from this disease. The search for effective treatment regimens and new approaches to the management of patients with coronavirus disease in order to reduce the severity of coronavirus disease, reduce mortality, the number of complications and improve the rehabilitation period is very important nowadays. The aim of the work. To determine the main causes of mortality in patients with severe COVID-19 by analyzing the frequency and structure of complications in deceased patients. Materials and methods. The study conducted a retrospective analysis of 122 medical charts of deceased patients with COVID-19 who were hospitalized in a communal non-profit enterprise “Kyiv city clinical hospital №17” for the period from September 2020 to November 2021. Results and discussion. The overall mortality among patients with COVID-19 was 9.3%, in the intensive care unit (ICU) – 48.4%. The most common causes of death in patients with COVID-19 were: respiratory failure (RF) – 100% of cases, pulmonary embolism (PE) and acute heart failure (AHF) - about 60%. The average length of stay of patients in inpatient treatment was 11.67 ± 8.05 days, and in the intensive care unit – 7.94 ± 6.24 days. The mean age of patients hospitalized in the ICU was 63.5 ± 12.9 years and the mean age of patients who died was 71.2 ± 10.29 years. Prognostically significant criteria for lethal consequences were the presence of comorbidity: cardiovascular diseases- 92.3%, endocrine system diseases – 28.4%, nervous system diseases – 23.07%, kidney diseases – 9.6%, cancer – 9,6%, autoimmune conditions – 7.69%, varicose veins – 5.7%, respiratory system diseases – 5.7%. In patients with fatal outcome lymphopenia (84.6%) was observed in patients on admission to the ICU. Vasopressor and inotropic support was performed in 50 % of patients with COVID-19. In 25 % of those who died during long-term treatment and long-term respiratory support, there was the development of multiple organ failure, which in most cases was the point of no return. Conclusions. The most common causes of death were: respiratory failure, thrombosis, acute cardiovascular failure, sepsis and multiple organ failure. The main nature of the complications is common, but the cohort may be affected by different factors and the percentage of complications may differ in other hospitals.