BACKGROUND: Invasive bacterial infection is a considerable cause of morbidity and mortality in children. An overall view of the spectrum of invasive bacterial diseases is essential to the establishment of public health priorities. Information regarding the causative bacteria with respect to the age of affected patients and the site of infection, and case-fatality rate is invaluable in the empirical selection of antimicrobial agents. METHODS: One-hundred-and-fifteen episodes of invasive infections in presumably immunocompetent children at ages from 2 months to 15 years at the Seoul National University Children's Hospital, were reviewed retrospectively. Cases with nosocomial infection or underlying conditions that predispose to infection were excluded. RESULTS: The most common clinical entities were bacteremia without an identified focus (37%), followed by meningitis (28%), bacteremic pneumonia or empyema (18%) and bone and joint infection (15%). Staphylococcus aureus (24%), Streptococcus pneumoniae (24%), Salmonella species (23%), Haemophilus influenzae (14 %) and Streptococcus species (4%) together accounted for 90% of all cases. S. aureus was the most common pathogen in bacteremic pneumonia or empyema and bone and joint infection. S. pneumoniae together with H. influenzae were the most common causes of meningitis. The most common organism responsible for bacteremia without an identifiable focus was Salmonella species. The case-fatality rate was 4.8% for all cases of invasive infection. CONCLUSION: We reviewed the relative frequency of bacteria as etiological agents of invasive infections in children. The data may be useful in the establishment of public health priorities and serve as a reference for selection of antibiotics in the empirical therapy of suspected invasive bacterial infections.