Much progress has been made in the understanding of nosocomial pneumonia but important issues in diagnosis and treatment remain unresolved. The controversy over diagnostic tools should be closed. Instead, every effort should be made to increase our ability to make valid clinical predictions about the presence of ventilator associated pneumonia and to establish criteria to guide restricting empirical antimicrobial treatment without causing patient harm. More emphasis must be put on local infection control measures such as routine surveillance of pathogens, definition of controlled policies of antimicrobial treatment, and effective implementation of strategies of prevention.