Community-acquired pneumonia (CAP) is a common disease and a frequent cause of morbidity and mortality worldwide. It puts an enormous burden on medical and economic resources, particularly if hospitalization is required. Initial antibacterial therapy for CAP is usually empirical, as culture and antibacterial sensitivity test results are rarely available at initial diagnosis. Any agent selected for empirical therapy should have good activity against the pathogens commonly associated with CAP, a favorable tolerability profile, and be administered in a simple dosage regimen for good compliance. Streptococcus pneumoniae remains the most common causative pathogen, although the incidence of this organism varies widely. Streptococcus pneumoniae strains with decreased susceptibility to penicillin have become increasingly prevalent over the past 30 years and are now a serious problem worldwide. In addition, an increase in the prevalence of pneumococci resistant to macrolides has been observed in Europe over recent years. Mycoplasma pneumoniae and Chlamydia pneumoniae are among the most common atypical pathogens isolated from patients with CAP. Haemophilus influenzae, Staphylococcus aureus and Moraxella catarrhalis are less commonly identified as causative organisms. The emergence and spread of resistance to commonly used antibiotics has challenged the management of CAP. Multiple sets of CAP guidelines have been published to address the continued changes in this complex disease.