Despite significant progress in the field of prevention, early diagnosis and antibacterial therapy, community-acquired pneumonia still retains the status of not only the most common among acute infectious diseases, but is also a frequent source of sepsis, which greatly increases the likelihood of death in this group of patients. The purpose of the study was to perform a comparative analysis of clinical and laboratory parameters and assess the nature of their changes in the first 48 hours from the moment of verification of sepsis that developed against the background of pneumonia in patients of the therapeutic department, depending on the outcome of hospitalization.Clinical groups and research methods. A retrospective comparative study was carried out, which included, using a continuous sampling method, patients with sepsis that developed against the background of pneumonia in patients hospitalized in therapeutic clinics of the Federal State Budgetary Educational Institution of Higher Education Siberian State Medical University of the Ministry of Health of Russia in the period from 01/01/2019 to 04/30/2023. In total, the study included 40 patients of both gender, followed by division into two comparison groups depending on the outcome of hospitalization (discharge from hospital or death) for the dynamic assessment of clinical, anamnestic and laboratory parameters in the early stages of the development of a septic condition (the first 48 hours) in order to determine their relationship with the outcome of hospitalization.Results. All patients were divided into 2 groups. The first group (n=17, 42.5 %) consisted of patients with a favorable outcome of hospitalization (recovery), the second group (n=23, 57.5 %) consisted of patients with a fatal outcome. At the time of verification of sepsis, patients with a favorable outcome had a significantly lower SOFA score (3 (2; 6) points) than patients with a fatal outcome (6 (5; 7) points), p = 0.037. The change in urea concentration in the first 48 hours from the moment of verification of sepsis, which in the group of survivors was -1.3 (-4.4; 1.99) mmol/l, and in the group of deceased 5.5 (-1.5; 12. 2) mmol/l, p=0.020. In the group of deceased patients, 8 people (34 %) at the time of verification of sepsis had a combination of hypotension (<90/60 mm Hg) and serum lactate >5 mmol/l. In the survivor group, hypotension was observed in only 2 people (11 %), and lactate levels in these patients were in the range of 4.5- 4.6 mmol/l. At point 1, the indicators of immature granulocytes were not statistically significantly different between surviving and deceased patients (1.2 (0.7; 2.1)% vs 0.8 (0.6; 1.5)%, respectively, p>0. 05). After 48 hours, the level of immature granulocytes increased in surviving patients to 1.5 (1; 3.2)% and, conversely, decreased to 0.65 (0.45; 1.45)% in the group of deceased patients, and the difference in these indicators between groups became statistically significant, p <0.05.Conclusion. Thus, in patients with sepsis against the background of severe pneumonia, the mortality rate was 57.5 %. In order to identify groups at high risk of death due to sepsis due to pneumonia, in addition to the SOFA scale, dynamic monitoring of biomarkers such as urea, lactate, immature granulocytes and reticulocytes should be carried out in the first 48 hours from the moment of verification of the septic state.