Lower respiratory tract infections (LRTIs) are among the most common infections treated by health care providers. They include a variety of infections ranging from mild acute viral bronchitis to life-threatening ventilatorassociated pneumonia. Despite advances in general knowledge concerning such diseases, there remains considerable morbidity and mortality with many LRTIs. LRTIs are also the cause of a great deal of antibiotic use. Although community-acquired pneumonia and ventilator-associated pneumonia generally require antimicrobial therapy for optimalmanagement, almost all cases of acute bronchitis are not caused by bacteria and do not warrant antibacterial agents. Use of antibacterials for acute viral bronchitis is a source of antimicrobial overuse and increases the likelihood of increasing antibiotic resistance. For patients with LRTIs who warrant antimicrobials therapy, most recent guidelines recommend individualizing antimicrobial therapy based on stratification of patient risk factors (eg. underlying conditions and recent use of antibiotics) to assist in optimal antibiotic usage. Since 1998, when LRTIs were last featured in the Infectious Disease Clinics of North America (volume 12, number 3), new information concerning significant aspects of these infections has been published. These include etiology and epidemiology, impact of antimicrobial resistance, diagnostic testing, and considerations of management. This issue reviews many of the important characteristics and management issues (including pathophysiology, diagnosis, management, and prevention) of LRTIs in light of recent information and published guidelines.