Nosocomial pneumonia is the second most frequent nosocomial infection and represents the leading cause of death due to hospital acquired infections. In recent years, evidence has accumulated that initial inappropriate antibiotic treatment is an important and independent mortality risk factor for patients with nosocomial pneumonia. On this point, several authors have found that delaying the administration of appropriate antibacterial treatment is associated with an excess in hospital mortality. In this scenario, various strategies have been proposed, such as de-escalation therapy, that attempt to balance the need to provide appropriate initial treatment with limiting the emergence of antibacterial resistance. Another relevant point is the duration of antibiotic therapy: international guidelines suggest that it should be based upon the clinical response, with a standard duration of 14-21 days, but several authors have shown that a shorter course could lead to the same clinical results, and significantly reduce both antimicrobial consumption and the emergence of resistant pathogens. The present review deals with the clinical importance of early, shorter antibiotic therapy.