Ventilator-associated pneumonia occurs in 10% to 65% of critically ill patients and is associated with increased length of stay in the intensive care unit and increased risk of death. Prevention of this condition includes strategies designed to minimize bacterial contamination of the airway, ventilator circuit, and secretions and strategies designed to minimize aspiration of gastric contents. The best strategy for the diagnosis of ventilator-associated pneumonia remains controversial; it remains to be proved that use of bronchoscopic specimens is associated consistently with improved outcomes. Initial treatment for ventilator-associated pneumonia is equally controversial. Recent work, however, suggests that the provision of adequate coverage with broad-spectrum antibiotics is associated with better clinical outcomes than the use of more narrow spectrum agents that may be inadequate.