Mechanically ventilated patients have disproportionately high rates of pneumonia compared with nonintubated patients. The presence of an endotracheal tube circumvents natural host defenses, causes local trauma and inflammation, and increases the risk for aspiration of nosocomial pathogens from the oropharynx. Due to the high fatality rate of nosocomial pneumonia and the poor outcomes despite the use of appropriate antibiotic therapy, efforts have been directed at the prevention of infection. Efforts have included the discrete use of antibiotics, compliance with standard infection control techniques, a knowledge of the risks associated with respiratory therapy equipment, proper patient positioning to reduce the chance of gastric reflux, reduction of gastric overgrowth with bacteria, and in some patients, local antibiotics to reduce colonization in the oropharynx and gastrointestinal tract. Sir William Osler called pneumonia "the Captain of the men of death." Although progress has been made to reduce the rank from Captain, greater efforts are needed to improve our understanding of pathogenesis, prevention, diagnosis, and treatment of this infection.