Objective: Nosocomial bloodstream infections are serious health problems in hospitals all over the world. They are associated with a high rate of morbidity and mortality, prolonged hospital stay and higher costs. The aim of this study was to evaluate the clinical outcomes of the patients with gram-negative bacteremia and to identify the risk factors for mortality. Material and Methods: A prospective observational study was performed in the 1196-bed Ankara Numune Education and Research Hospital. The patients with nosocomial gram-negative bacteremia were included in the study from July 2006 to June 2008. Bacteremia was considered to be nosocomial when it was diagnosed at least 48 h after hospital admission. Gram-negative bacteremia was defined as the presence of gram-negative bacteria in the blood, documented by at least 1 positive hemoculture. In patients who had more than one episode of gram-negative bacteremia, only the first episode was considered. Antibiotic therapy was considered to be appropriate if the drugs used had in vitro activity against the isolated strain. Results: Among the 253 cases (mean age: 54.5 +/- 20 years old, male/female: 159/94) of Gram-negative bacteremia included in the study, the most frequently detected microorganisms were Escherichia colt (n=96, 37.9%), Acinetobacter spp. (n=54, 21.33%), Pseudomonas aeruginosa (n=41, 16.2%), Klebsiella spp. (n=39, 15.4%), Enterobacter spp. (n=9, 3.5%) and Stenotrophomonas maltophilia (n=6, 2.3%). The mean duration of hospital stay until Gram-negative bacteremia was 19 +/- 17 (range 3-82) days. Mortality rates at 14 days and at 30 days after the bacteremia were, respectively, 28.5% and 38.4%. We found that Acute Physiology and Chronic Health Evaluation (APACHE) II score over 20, inappropriate antibiotic treatment, receiving total parenteral nutrition, unconsciousness and thrombocytopenia were significant independent risk factors for mortality at day 30 after the Gram-negative bacteremia. Conclusion: Awareness of mortality risk factors is important for the prognosis. Appropriate antibiotic treatment could decrease deaths associated with Gram-negative bacteremia.