A blood culture (BC) is frequently requested in both patients with a suspected occult bacteremia/invasive infection as well as those with certain focal infections. Few data are available on the characteristics of patients in whom a bacteremia is identified in the Pediatric Emergency Department (PED). A prospective multicenter registry was established by the Spanish Pediatric Emergency Society. Epidemiological data, complementary test results, clinical management, and final outcome were recorded. Data from the first three years of the registry were analyzed. A true bacterial pathogen grew in 932 of 65,169 BCs collected [1.43 %; 95 % confidence interval (CI) 1.34-1.51 %], with 711 of them collected in patients without previously known bacteremia risk factors. Among them, 335 (47.1 %) were younger than 1 year old and 467 (65.7 %) had a normal Pediatric Assessment Triangle (PAT) on admission. Overall, the most frequently isolated bacterial species was Streptococcus pneumoniae (27.3 %; 47.6 % among patients with an altered PAT). The main pathogens were Escherichia coli (40.3 %) and S. agalactiae (35.7 %) among patients younger than 3 months, S. pneumoniae among patients 3-60 months old (40.0 %), and S. aureus (31.9 %) among patients over 60 months of age. Neisseria meningitidis was the leading cause of sepsis in patients older than 3 months. Eight patients died; none of them had a pneumococcal bacteremia and all had abnormal PAT findings on admission. S. pneumoniae is the main cause of bacteremia in patients without bacteremia risk factors who attended Spanish PEDs. Age and general appearance influence the frequency of each bacterial species. General appearance also influences the associated mortality.