Although chronic eosinophilic pneumonia is a well-known disorder, acute eosinophilic pneumonia has not been as well described. We described the clinical features of two patients with acute eosinophilic pneumonia. The patients presented with an acute onset of high fever, severe hypoxemia and diffuse pulmonary infiltrates. Eosinophilic pneumonia was diagnosed by bronchoalveolar-lavage and confirmed by transbronchial lung biopsy. We believe that we have described an acute type of eosinophilic lung disorder which can not be applied to Crofton's classification of PIE, so we reviewed previously reported cases of acute eosinophilic pneumonia and tried to summarize their clinicopathological features. We also emphasized the existence of eosinophil infiltration into the bronchial wall in Acute Eosinophilic Pneumonia.