Community-acquired pneumonia has a significant impact upon healthcare in North America and worldwide. In the U.S. it is responsible for three to four million cases yearly and 78 000 deaths. It is not a homogeneous entity and it may be caused by a number of pathogens includingStreptococcus pneumoniae, the atypicals (Mycoplasma pneumoniae,Chlamydia pneumoniaeandLegionellaspecies)Haemophilus influenzaeand Gram-negative rods. While it is clear that directed therapy is the ideal, empiric therapy is likely to remain the norm for some time to come. This is because of limitations in current diagnostic techniques, the possibility of infection with co-pathogens and the broad spectrum of antimicrobial activity required to treat the various pathogens which may be responsible for infection in any given patient. Of great concern is the increase in the incidence of resistant pathogens seen in community-acquired pneumonia. Of particular significance are the isolates ofS. pneumoniaewhich display resistance to penicillin and macrolides although the exact clinical relevance has yet to be determined. New guidelines for the treatment of community-acquired pneumonia have been developed by the Infectious Disease Society of America which include the new fluoroquinolones. These agents offer the potential for monotherapy of community-acquired pneumonia in cases which previously required combination regimens such as a macrolide and a beta-lactam. There is great concern however, that these agents not be used inappropriately thereby hastening the emergence of resistance to the fluoroquinolone class of antimicrobials.