No single test will provide all the information needed to diagnose ventilator-associated pneumonia (VAP), and the clinician must use multiple clinical criteria for the diagnosis. The use of culture techniques allows one to enhance the sensitivity and specificity of the diagnosis of pneumonia. In addition, the clinician can be kept up to date about potential new pathogens as they occur in the intensive care unit. Knowledge of the local flora allows one to make a better choice of empiric therapy for VAP.