OBJECTIVES. The aim of this study was to identify the frequency and epidemiological characteristics of infections of critically ill patients, who require intensive care and investigation of possible risk factors responsible for complications of infections. STUDY DESIGN. Retrospective study. PARTICIPANS AND METHODS. Study included 207 patients (median age 65 years, from 54 to 74) treated in ICU at the Clinic of anaesthesiology form 1st January 2013 to 31st March 2016 whose treatment was complicated due to a hospital infection. The data was obtained from medical records and was statistically processed with SPSS. The processed patients were those affected with resistant hospital infections respectively. RESULTS. Hospital infection affected 6.9% of the patients (15 to 1000). In 30.1% of the cases the infection was identified during the admission of the patient, and in 69.9% during the time spent in ICU. There was a considerable percentage of surgical patients. The most common infections are infections of the respiratory system (62.1%) and sepsis (18.4%) and the most common cause is Acinetobacter baumanii (87%). Being exposed to surgical intervention, the presence of an artificial airway and the duration of hospitalization are observed as independent predictors for development of infections in ICU. Surgical infection is the biggest predictor. High initial SAPS II score (>58) indicates unfavourable outcome of the treatment. CONCLUSION. Most of the respondents are surgical patients. One third was admitted to ICU with identified infection, and the rest of the patients developed infections during their stay in ICU. Most common are pneumonia, tracheitis and sepsis. The occurrence of these infections is connected with invasive procedures including endotracheal intubation, surgical intervention and with the number of days spent in ICU. Dominant cause of hospital infections in ICU is multiresistent Acinetobacter baumanii.