Nosocomial pneumonia complicates the course of a large number of hospitalized patients, associated with a higher risk of death, prolonged length of stay and over-costs. Rates of pneumonia are considerably higher in the ICU, in the post-operative period, particularly in patients treated with mechanical ventilation. Microorganisms responsible for nosocomial pneumonia are frequently multiresistant, particularly in case of late-onset pneumonia and in patients receiving prior antimicrobial therapy. Management of patients suspected of having nosocomial pneumonia aims to identify patients with true lung infection and not only colonization of the lower respiratory tract, to identify responsible pathogen(s) and to optimize the choice of antimicrobial therapy. To do that, bronchoscopic techniques with the use of bronchoalveolar lavage or protected specimen brush have the best sensitivity and specificity. Appropriate antimicrobial treatment must be initiated without delay. The potential interest of combination therapy, nebulized antibiotics needs to be clearly demonstrated by further investigations; similarly the optimal duration of treatment ensuring efficacy and avoiding the emergence and development of infections due to multiresistant pathogens remains to be more precisely evaluated.