The article is devoted to the analysis of morbidity, mortality, risk factors and etiology of nosocomial bloodstream infections in Poland. The analysis was based on nationwide data collected in nosocomial infections surveillance system co-coordinated by the Polish Society of Hospital Infections in 1999 in 120 hospitals. There were 513,807 patients included in the study, among whom 11,157 cases of nosocomial infections were detected. In this group 332 cases of nosocomial bloodstream infections (BSI) were detected, from this number 187 was the only detected site of infection (the rate of this infection was 1.9%). The highest mortality connected with BSI was observed among newborn children and in intensive care units (morbidity rate was 28.7 for 1,000 admissions). Mortality attributable to BSI was 9.1% among all BSI cases. The results of the analysis show that there is a statistically important increase of morbidity and mortality rates attributable to BSI among patients with vascular catheters in comparison to general population. There was also a detailed analysis of connection between the weight of newborn children and occurrence of BSI. In almost 80% of detected cases of BSI laboratory tests were performed in order to identify the etiological factor. According to the results of these tests dominant etiological factors were: Staphylococcus aureus (19.6%) from which almost 60% were MRSA, CNS (19.2%) from which about 10% were strains resistant to teicoplanin and Klebsiella spp. (15.7%) from which 60.4% were strains resistant to ceftazidime. There was also a separate analysis of etiological factors of BSI and their resistance to antibiotics among children.