AIM: To evaluate epidemiology of sepsis in medical intensive care unit (ICU) in a university hospital, and the impact of ICU performance and appropriate empirical antibiotic therapy on survival of septic patients. METHODS: Observational, partly prospective study conducted over 6 years assessed all patients meeting the criteria for sepsis at ICU admission at the Sisters of Mercy University Hospital. Clinical presentation of sepsis was defined according to 2001 International Sepsis Definitions Conference. Demographic data, admission category, source of infection, severity of sepsis, ICU or hospital stay and outcome, ICU performance, and appropriateness of empirical antibiotic therapy were analyzed. RESULTS: The analysis included 314 of 5022 (6.3%) patients admitted to ICU during the study period. There were 176 (56.1%) ICU survivors. At the ICU admission, sepsis was present in 100 (31.8%), severe sepsis in 89 (28.6%), and septic shock in 125 (39.8%) patients with mortality rates 17%, 33.7%, 72.1%, respectively. During ICU treatment, 244 (77.7%) patients developed at least one organ dysfunction syndrome. Of 138 (43.9%) patients who met the criteria for septic shock, 107 (75.4) were non-survivors (P<0.001). Factors associated with in-ICU mortality were acquisition of sepsis at another department (odds ratio [OR] 0.06; 95% confidence interval [CI], 0.02-0.19), winter season (OR 0.42; 0.20-0.89), limited mobility (OR 0.28; 0.14-0.59), ICU length of stay (OR 0.82; 0.75-0.91), sepsis-related organ failure assessment (SOFA) score on day 1 (OR 0.80; 0.72-0.89), history of global heart failure (OR 0.33; 0.16-0.67), chronic obstructive pulmonary disease (COPD)-connected respiratory failure (OR 0.50; 0.27-0.93), septic shock present during ICU treatment (OR 0.03; 0.01-0.10), and negative blood culture at admission (OR 2.60; 0.81-6.23). Microbiological documentation of sepsis was obtained in 235 (74.8%) patients. Urinary tract infections were present in 168 (53.5%) patients, followed by skin or soft tissue infections in 58 (18.5%) and lower respiratory tract infections in 44 (14.0%) patients. Lower respiratory tract as focus of sepsis was connected with worse outcome (P<0.001). Empirical antibiotic treatment was considered adequate in 107 (60.8%) survivors and 42 (30.4%) non-survivors. Patients treated with adequate empirical antibiotic therapy had significantly higher survival time in hospital (log-rank, P=0.001). CONCLUSION: The mortality rate of sepsis was unacceptably high. The odds for poor outcome increased with acquisition of sepsis at another department, winter season, limited mobility, higher SOFA score on day 1, history of chronic global heart failure, COPD-connected respiratory failure, and septic shock present during ICU treatment, whereas longer ICU length of stay, positive blood culture, and adequate empirical antibiotic therapy were protective factors.