The antibiotic management of infants and children with pneumonia is based on the clinician's assessment of the most likely infecting pathogens, the susceptibilities of the infecting pathogens and the seriousness of the illness. The bacterial etiology of pneumonia changed significantly following the universal use of protein-conjugated vaccines for Haemophilus influenzae type b. Similar significant changes are likely to occur with universal use of protein-conjugated vaccines for Streptococcus pneumoniae, requiring the clinician to alter assumptions of the risk of invasive bacterial infection in the child who presents with pneumonia. New strategies are likely to require fewer ancillary tests (e.g. white blood cell count, C-reactive protein and blood culture) and suggest a decreased need for empiric antibiotic therapy. Although the majority of lower respiratory tract infections in children have a viral etiology and are not amenable to antibiotic therapy, for the seriously ill child who is thought to be likely to have pneumonia caused by a bacterial pathogen, recent changes in the susceptibility patterns of both common organisms such as S. pneumoniae and more unusual pulmonary pathogens such as Staphylococcus aureus have forced changes in the selection of both empiric and definitive antibiotic therapy. Third generation cephalosporins ceftriaxone and cefotaxime appear to be effective therapy for pneumonia caused by virtually all current isolates of S. pneumoniae. In contrast antibiotic regimens for life-threatening pulmonary infections in which Staphylococcus aureus is a suspected pathogen should include vancomycin.