Background: Bloodstream infections are an increasing problem and currently , represent a threat to public health, overcoming diseases such as HIV. Bacteremia accounts for approximately 15% of all nosocomial infections and affects 1% of all hospitalized patients. Aim: To describe the clinical, epidemiological and microbiological characteristic of episodes of nosocomial bacteremia occurring in a Colombian hospital. Methods: Retrospective, observational, cross-sectional study including adult patients, hospitalized in the internal medicine unit at the University Hospital of Santander, Bucaramanga, Colombia, during years 2014 to 2016, who met the criteria of the CDC for bloodstream infection. The protocol was approved by the Hospital Ethics Committee and by the Research Ethics Committee of the Industrial University of Santander. Results: We reviewed 450 clinical records with 148 patients and 182 microbiological isolates. 53% were male. The most frequent comorbidities were: high blood pressure (46.6%), HIV infection (29.7%). The vascular and urinary systems were the most frequent anatomical sites as the source of the infection (respectively 37.3% and 38.3%). Case fatality rate was 29%. The pathogens most frequently isolated were: Klebsiella pneumoniae, Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa (globally: 49.8%) and Staphylococcus autrus 12.1%. The multivariate analysis showed a relationship between anemia and in-hospital mortality (OR =17.3, 95%CI 2.95-102.0). Conclusions: Bacteremia is a frequent infection during hospital care that presents high mortality. It is noteworthy the predominance of Enterobacteriaceae isolates with broad profiles of resistance. The history of HIV infection is one of the most frequent which deserves to be evaluated as a risk group.