Acute infections are one of the leading causes of admission to intensive care unit and their incidence is increasing. As the patients treated in intensive care unit are often in bad condition, of older age and often exposed to many invasive procedures, the mortality of infections is high. One of the most common infections are sepsis, pneumonia and urinary tract infections. A retrospective study was conducted among the patients treated in Intensive care unit of the Sisters of Charity University Hospital Centre in the period between January 1st 2018 and December 31st 2018. The aim of the study was to analyse the frequency and outcomes of infections in the unit and to investigate the most common pathogens causing the infections. The study included 761 patients whose leading reason for admission was sepsis which accounted for 27.9%. The total mortality was 23.4%, the mortality of sepsis was 37.7% and the mortality of sepsis combined with sepsis shock was 64.6%. The most common pathogens were Escherichia coli, Staphylococcus spp. and Klebsiella pneumoniae. Moreover, 346 cases of non-septic infections were noted among the 549 patients who were not treated for sepsis. Among the infections of interest, the most common were urinary tract infection (25.7% of all cases) followed by pneumonia (19.7%), acute exacerbation of chronic obstructive lung disease (13.1%) and soft tissue infection (4.6%). The most frequent pathogens isolated in those infections were Escherichia coli, Streptococcus pneumoniae, Haemophilus influenzae and Pseudomonas aeruginosa. The mortality of patients with acute non-septic infections as their main illness or as the complication of another condition was between 12 and 27.8%. In comparison with earlier studies, the frequency of sepsis is found to be several times higher, the sepsis mortality is also increasing while the sepsis shock mortality has not changed. The pathogen profile shows a low incidence of bacteria with high multi-resistency potential. Our results are consistent with the results of larger European and world studies.