Nosocomial pneumonia is the second most common intrahospital infectious complication. The incidence of nosocomial pneumonia is particularly high in mechanically ventilated patients. During the period covered by this review many articles have been published reporting on important advances in epidemiology and etiology. New diagnostic procedures, eg, protected bronchoalveolar lavage, have been described, and some have been validated using immediate postmortem pulmonary biopsies. In addition, the matter of prevention has been productively addressed in many studies during this period. Mechanical and physical prevention mechanisms have been acknowledged as playing an important role in reducing the incidence of nosocomial pneumonia, whereas others, such as selective digestive decontamination, remain controversial. There has been relatively little progress made regarding changes in antibiotic treatment. Of crucial importance for future research are the recent developments in human and murine monoclonal antibodies against endotoxins released during gram-negative septicemia. The insights obtained through this research will undoubtedly prove beneficial in the fight against those nosocomial pneumonias caused by these microorganisms.