Streptococcus pneumoniae, the most important respiratory tract pathogen implicated in community-acquired pneumonia (CAP), is becoming increasingly resistant in vitro to the beta -lactams and macrolides, and fluoroquinolone resistance has been detected. A growing body of evidence suggests that prolonged antimicrobial use may contribute directly and indirectly to increased antimicrobial resistance among common respiratory pathogens. Long-term exposure to antimicrobial agents, especially less-potent agents, directly increases selection pressure for resistance. Indirectly, poor patient compliance, multiple daily dosing, and the increased risk of adverse events further complicate the resistance issue and diminish the efficacy of long-term antimicrobial use. Controlled clinical trials addressing the appropriate duration of therapy for CAP are lacking. However, available data suggest that with appropriate antibiotic selection, based on appropriate spectrum, potency, and pharmacokinetic/pharmacodynamic profile, lower respiratory tract infections in outpatients can be successfully treated in <7 days rather than the 7-14 days currently recommended.