Objectives: to take stock of epidemiology, diagnostic methods and the ecology and bacterial resistances of nosocomial respiratory infections, in order to propose preventive measures to improve the management of patients under mechanical ventilation. Type of study: retrospective, analytical, epidemiological over a period of 30 months, from 1 January 2014 to 31 June 2016 conducted in the laboratory of microbiology of University hospital HASSAN II of Fez. Patients and methods: All distal protected specimens (PDP), and bronchoalveolar lavages (BAL) positive from intubated patients hospitalized in resuscitation services. The identification of the bacterial strains as well as the antibiogram was carried out by automated method and the phenotypes of resistance were determined by the diffusion methods in MH agar medium according to the recommendations of the CASFM / EUCAST. Results: A total of 905 respiratory specimens were received of which 547 were positive (60%). VAPs were due to bacteria that were potentially resistant to antibiotics. Acinetobacterbaumanii was the most represented bacterium responsible for 33% of pneumonia acquired under mechanical ventilation. Conclusion: In our series, potentially multi-resistant antibiotic bacteria and especially Gram-negative bacilli were the pathogens most often responsible for VAPs. The choice of the probabilistic antibiotic therapy of the early PAVM must take into account all the risk factors of bacteria potentially multi-resistant to the antibiotics and not only its time of appearance.