Introduction.Neonatal sepsis is often suspected in hospitalized newborn infants, but only in 25-30% of cases it is confirmed via a positive culture. Selecting the antibiotics based on local epidemiology favors their rational use and minimizes their side effects.Primary objective. To describe the prevalence of early-and late-onset sepsis with microorganism isolation and their clinical characteristics. Population and method.Retrospective, cross-sectional study conducted between 01-01-2013 and 12-31-2017 in a public maternity center of Argentina in all hospitalized newborn infants with a diagnosis of early-and late-onset sepsis with microorganism isolation, and those re-admitted in their first month of life.Results. A total of 3322 newborn infants were admitted; 1296 were assessed for suspected earlyonset sepsis; 25 had a positive culture (1.9%; rate: 0.86‰). Of these, 52% were born before 33 weeks of gestation. Microorganisms: Escherichia coli 5, Listeria monocytogenes 4, Streptococcus agalactiae (SGB) 3, Streptococcus pneumoniae 3. Also, 68% of late-onset sepsis cases (rate: 8.73‰) occurred in infants born before 33 weeks of gestation. Hospital-acquired microorganisms: coagulase-negative