Abstract: Objective: To enhance our awareness of aspiration pneumonia following mechanical ventilation.Methods: 31 cases of mechanically ventilated patients with aspiration pneumonia were reviewed.Results: There were 59 case times of aspiration pneumonia diagnosed in these patients. The incidence was directly proportional to the duration of artificial airway. Most of aspiration pneumonia appeared in endotracheal intubation patients （43 cases, 72.9%）. The high risk factor included wrong manner of feeding through nasogastric tube and aspiration of sputum, long lasting time of artificial airway and feeding tube placing. The clinical manifestations were fever, productive cough, dyspnea, pulmonary moist rales, peripheral neutrophilia and new infiltration patches on chest radiograph. Gram negative bacteria （especially Pseudomonas aeruginosa and klebsiella pneumonia） were the dominant aerobic pathogens. 17 cases had successful extubation but the other 14 patients died.Conclusion: Aspiration pneumonia is the common complication of mechanical ventilation. The prognosis may be improved by aggressive treatment and reasonable prophylaxis.